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  • 10th Class Physics Chapter 18: Atomic and Nuclear Physics

    10th Class Chapter 18: Atomic and Nuclear Physics Short and Simple Question & Answer

    In this post, you will find solved notes of 10th class physics chapter 11 in PDF. There are no obscure words in these notes, they are simple and well organized. You can download these notes by clicking on the download button at the bottom of this page. View or download these Physics Chapter 11 Audio Notes for Class 10 English Medium. Many students have successfully used the Physics Estimate Paper 2024 by Faiz Ul Islam to achieve good results in their exams.

    Q 1. Define atom and write down its parts.

    Ans: The smallest part of an element is called an atom. Parts of atom: Atom consists of two parts and its central part is called nucleus. The nucleus consists of protons and neutrons. The proton ls a positively charged particle and neutron has no charge so the nucleus carries a positive charge. The electrons revolve around the nucleus ln nearly circular orbits. Since an atom ls a neutral particle, so the number of electrons in it is equal to the number of protons.

    Q 2. What are Nucleons?

    Ans: The mass of the proton & neutron is nearly the same i.e. 1.67 x 1027 kg. Since the protons and neutrons exist inside the nucleus so these are called nucleons.

    Q 3. What is Atomic Mass Number?

    Ans: A nucleon is nearly 1836 times heavier than an electron. So the mass of an atom is nearly equal to the total sum of the masses of all the protons and neutrons present in the nucleus of that atom. “The total number of protons and neutrons in the nucleus is called the Atomic Mass Number and is denoted by the letter A”.

    Q 4. What is Atomic Number?

    Ans: Since the number of protons in an atom of different elements is different so the number of protons in the nucleus indicates the charge on that nucleus. “The number of protons ln a nucleus is called the charge number or Atomic number and is denoted by the letter Z”. The number of neutrons in the nucleus is denoted by the letter N.

    Q 5. What do you know about Nuclide?

    Ans: If atomic number of an atom is Z and its Atomic Mass Number is A then this atom is represented by the symbol which is called a nuclide ZX A . For example, there is only one proton in the nucleus of hydrogen atom so its atomic number is 1 and its atomic mass is also 1. Hence it is denoted by 1H 1 .

    Q 6. What is the difference between Atomic number and Atomic Mass number?

    Ans: Atomic Number: The total number of protons and neutron in the nucleus is called the atomic mass number. It is denoted by the Latter A. Atomic Mass Number: The number of protons in a nucleus is called the charge number or atomic number. It is denoted by the letter Z. Q 7. What are radioactive isotopes? Ans: The atoms of the same radioactive element whose atomic numbers are the same but have different atomic mass numbers are called Radioactive isotopes.

    Q 7. What are isotopes? What do they have in common and what are there differences.

    Ans: Atoms of the same element having name atomic number but different mass number, are called isotope. They have same chemical properties but different physical properties.For example, Hydrogen has three isotopes: Protium Z = 1, A = 1, N = A – Z = 0 Detitrium Z = 1, A = 2, N = A – Z = 1 Tritium Z = 1, A = 3, N = A – Z = 2 Hence, from above relations we conclude that the number of protons are same and number of neutrons are different ln the isotopes of hydrogen.

    Q 8. Why Marie Curie and Pierre are famous?

    Ans: The most significant investigations of the process of radioactivity were done by Marie Curie and the husband Pierre. They discovered two new elements which emitted radiations. These were named polonium and radium. This process of emission of radiations by some elements was called natural radioactivity by Marie Curie.

    Q 9. Why are heavy nuclei unstable?

    Ans: Heavy nuclei are unstable due to large number of protons. The strong nuclear force cannot balance the repulsive Coulomb force which comes into play due to increase in size.

    Q 10. What is meant by Background Radiations?

    Ans: Background Radiations: “Radiations present in atmosphere due to different radioactive substances are called background radiations”. Sources of background radiations: The back ground radiation present in the atmosphere is due to the following two possible causes: i. The presence of radioactive material under the earth ii. The cosmic rays entering the earth from the upper atmosphere along with the sun light.

    Q 11. What are cosmic radiation?

    Ans: The earth and all living things on it also receive radiation from outer space. This radiation is called cosmic radiation which primarily consists of positively charged ions from protons to iron and large nuclei. The cosmic radiation interacts with atom in the atmosphere to create, a shower of secondary radiation, including x-rays, muons, protons, alpha particles, electrons and neutrons.

    Q 12. Describe a brief account of Interaction of various types of radiations with matter.

    Ans: α-radiation: It is a helium nucleus. When an alpha particle passes through a gas it interacts with the atom of the gas and ionizes them. As its mass is comparatively more than β and ɣ so it has less penetrating power. Each ionization by an α –particle produces an ion pair. The range of α particle is around 7cm and it can be stopped by a thick paper. Α particle are capable of producing fluorescence in zinc sulphide or barium platinocyanide. β-Radiations: these are negative charge particles they can penetrate 100 times more than α-particles. The β- particles loses most its energy in a single collision. Β- Particle can also produce fluorescence in some materials like barium platinocyanide. ɣ-Radiations: ɣ-rays have no charge that is why the cause very little ionization. The ɣ-ray photon can be absorbed by an atom and a photo electron can be ejected (photoelectric effect). When fast moving ɣ-ray photon is stopped it disintegrates into an electron positron pair (pair production). Material having large no of electron in a unit volume absorbs more ɣ-radiations. They have high penetration power than α & β particles and their intensity decreases exponentially with increase in depth of penetration into the material.

    Q 13. Explain how α and β -particles may ionize an atom without directly hitting the electrons? What is the difference in the action of the two particles for producing ionization?

    Ans: Since α and β particles are electrically charged they can cause ionization without hitting an atom either by attracting or repelling the electrons of the target atom. α particle produces ionization by exerting electrostatic force of attraction while β-particles produce ionization by exerting electrostatic force of repulsion. α-particles cause ionization by attracting the electron while β particles cause ionization by repelling the electron.

    Q 14. A particle which produces more ionization is less penetrating why?

    Ans: A particle which produces more ionization interacts strongly with the matter and loses its energy in a short distance and hence comes to rest soon, that’s why it is less penetrating.

    Q 15. If someone accidentally swallows an α-source and a β-source which would be the more dangerous to him? Explain why?

    Ans: α-particles have greater ionizing power as compare to β-particles. So, they can cause more damage to tissues, if swallowed.

    Q 16. Do α, β and ɣ Radiations emit from the same element? Why they are found in many radioactive elements?

    Ans: α, β and ɣ rays emit from the same element. But, an element cannot emit α and β rays simultaneously. When a radioactive element emits α and β rays, it decays into new element and so on. Hence, we find all the three radiations in many radioactive elements.

    Q 17. Define nuclear transmutation?

    Ans: “The spontaneous process in which a parent unstable nuclide changes into a more stable daughter nuclide with the emission of radiations is called nuclear transmutation”.

    Q 18. What is the use of α, β and ɣ radiation?

    Ans: α particles: They are used to treat skin cancer because their penetrating power is small. β particles: They are used to treat the tumors under the skin due to their large penetration power. ɣ particles: They are used to treat the infection in interior parts of the body clue to their longest penetration power. Q 22. What is the difference between an electron and β-particles? Ans: β particle is negatively charged particle emitted from the nucleus of radioactive element. An electron is negatively charge particle which revolves around the nucleus.

    Q 19. What do you know about half life?

    Ans: “The half-life of an element is that time during which the numbers of atoms of that element are reduced to one half’. Example: If the life time of a radioactive element is T, then at the end of this time the number of atoms in this element remain one half, after a time 2T, the number of atoms remain 25% and after time 3T, the number of atoms are reduced to 12.5% of initial number.

    Q 20. What is meant by Penetrating ability?

    Ans: Penetrating ability: The strength of radiations to penetrate a certain material is called penetrating power”. All kind of radiations penetrate but perpetrating range is different for each.

    Q 21. What are radioactive isotopes?

    Ans: The atoms of the same radioactive element whose atomic numbers are the same but have different atomic mass numbers are called Radioactive Isotopes.

    Q 22. What are stable nuclides?

    Ans: Nuclei which do not emit radiations naturally are called stable nuclei. Most of the nuclei whose atomic number is from 1 to 82 are stable nuclei: They do not change from one type of element to another. The stable elements can also be changed into unstable form by bombarding them with neutrons. Such elements are called, radio isotopes.

    Q 23. What are unstable nuclides’?

    Ans: Nuclei which do not emit radiations naturally are called stable nuclei. Some elements, whose atomic number is greater than 82, are naturally unstable. These elements depending upon their characteristics, emit, all the time, different types of radiations and they continuously change from one type of element to another.

    Q 24. What is a radioactive tracer? Describe one application each in medicine, agriculture and industry.

    Ans: A definite quantity of radio isotope introduced into a mechanical or biological system to enable its route through the system, as: i. Tracers are widely used in medicine to detect malignant tumors, blockage in the blood vessels, e.g. brain and thyroid tumors are detected using I-131. Radio sodium has been largely used in medical research to study the action of various medicines ii. Tracers are also used in agriculture to study the uptake of a fertilizer by a plant, e.g. P-32 is incorporated in fertilizer and added to the soil. iii. Tracer technique is also very useful in industry in detecting the cracks and leakage in the pipes and welding joints e.g. Iridium-192 is used to test the welds.

    Q 25. How can Radioactivity helps in the Treatment of Cancer?

    Ans: Medical applications of radio isotopes can be divided into two parts i.e. diagnostic and therapy. Some examples are as: i. Radiotherapy with ɣ-rays from cobalt-60 is often used in the treatment of cancer. The ɣ- rays are carefully focused on the malignant tissue. ii. Radioactive Iodine-131 is used to fight with cancer of the thyroid gland. iii. For Skin Cancer Phosphorus-32 or Strontium-90 may be used. They produce β radiation.

    Q26. How can radioactivity help in the treatment of Cancer?

    Ans: Radioactivity & Treatment of Cancer: Cancerous cells are always weak as compared to the normal cells, and hence are destroyed by firing β-radiation or ɣ-radiation from radioactive source. Sometimes encapsulated “seeds” made from radioactive source are implanted in the malignant tissues for local and short ranged treatment. For example: • ɣ -rays from Co-60 in general • Iodine-131 for treatment of cancer of thyroid gland. • Phosphorus-32 or strontium-90 may be used for skin-cancers.

    Q 27. How a radioisotope be used to determine the effectiveness of fertilizer?

    Ans: Radioactive phosphorus or nitrogen used as a tracer in agriculture, provide information about the best fertilizer to supply to a particular crop and, soil. Due to their use, varieties of crops such as rice, wheat and cotton have improved. Moreover, plants have shown more resistance to disease and give better yield and grain quality.

    Q 28 What is Positron?

    Ans: Positron is a particle with mass equal to the mass of an electron having opposite and equal charge.

    Q 29. What is means by Nuclear fission.

    Ans: Nuclear Fission: Nuclear fission takes place when a heavy nucleus, such as U- 235, splits or fissions, into two smaller nuclear by bombarding a slow moving (low- energy) neutron represent in equation.

    Q 30. Why does water is used to slow down the neutrons rather than lead?

    Ans: When neutrons collide with lead nuclei, they are bounced back. While lead atoms remain at rest due to their greater mass. But, I case of water, collision between neutrons and hydrogen nuclei, present is water is perfectly elastic. In this collision. Neutrons are slowed down, while proton starts moving.

    Q 31. Write a note on Einstein’s mass energy equation.

    Ans: ln classical physics, the various form of energy was related under the law of conservation of energy but no relationship was established between the energy and mass. In 1905, when Einstein gave his theory of relativity, it also contained the idea that the energy and matter are interchangeable. For this change an equation was also given which is known as Einstein’s mass- energy equation. It is E = mc2 Which means that if mass m of matter is converted into energy, then this will be equal to E, where in this mass-energy equation c is the speed of light that is 3 x 108 ms-1

    Q 32. What is do you know about Fission chain reaction Fission chain reaction.

    Ans: When a neutron reacts with a uranium nucleus, two or three neutrons are released. Every one of these reacts with next nuclei producing two or three more neutrons and hence, the number of available neutrons and the fission goes on increasing. Such a reaction is called the chain reaction.

    Q 33. Define Fusion Reaction.

    Ans: When two light nuclei combine to form a heavier nucleus, the process is called nuclear fusion”. Equation: If an atom of Deuterium is fused with an atom of Tritium, a Helium nucleus or alpha particle is formed as given:

    Q 34. Why it is more difficult to start a fusion reaction rather than fission reaction?

    Ans: Because, in bringing two nuclei closer to each other, great work has to be done against repulsive forces of nuclei. Hence, more energy is needed. On the other hand, fission may be proceeded with slow neutrons.

    Q 35. Discuss uses and the hazards of radiations.

    Ans: Some of harmful effects on human beings due to large doses or prolonged small doses of radiations. i. Radiation burns, mainly due to beta and gamma radiations, which may cause redness and sores on the skin. ii. Sterility (i.e. inability to produce children). iii. Genetic mutations in both human and plants. Some children are born with serious deformities. iv. Leukernia (Cancer of the blood cells) v. Blindness or formation of cataract in the eye.

    Q 36. Describe the precaution to minimize radiations dangers (safety measures) Precautions to minimize radiation dangers.

    Ans: Because we cannot detect radiations directly, we should strictly follow safety precautions, even when the radioactive sources are very weak. i. Sources should not be handled with tongs and for ceps. ii. The user should use rubber gloves and hand should be washed carefully after the experiment. iii. All radioactive sources should be stored in thick lead containers. iv. Never point radioactive source towards a person. v. Frequent visits to the radiation sensitive areas should be avoided.

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    These 10th class physics notes were prepared according to the syllabus of all Punjab boards. Boards other than Punjab do not follow class 10 physics notes. These Punjab boards are Gujranwala Board, Lahore Board, Faisalabad Board, Multan Board, Rawalpindi Board, Bahawalpur Sargodha Board, DG Khan Board, Sahiwal.

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  • 10th Class Physics Chapter 12: Geometrical Optics

    10th Class Chapter 12: Geometrical Optics Short and Simple Question & Answer

    In this post, you will find solved notes of 10th class physics chapter 11 in PDF. There are no obscure words in these notes, they are simple and well organized. You can download these notes by clicking on the download button at the bottom of this page. View or download these Physics Chapter 11 Audio Notes for Class 10 English Medium. Many students have successfully used the Physics Estimate Paper 2024 by Faiz Ul Islam to achieve good results in their exams.

    Q 1. What is reflection?

    Ans: Reflection of Light: When light traveling in a certain medium falls on the surface of another medium, a part of it turns back in the same medium. This is called the reflection of light. OR The bouncing back of light in the first medium after striking with any reflecting surface.

    Q 2. Define regular reflection and Irregular reflection.

    Ans: Regular Reflection: The reflection by a smooth surface in which all the reflected rays are parallel to each other is called regular reflection. Irregular Reflection: The reflection of light rays is not parallel to each other.

    Q 3. Write the conditions for regular and irregular reflection.

    Ans: Conditions for Regular Reflection:  The reflecting surface should be a plane surface.  The reflecting surface should be flat.  The reflected rays of light should be parallel to each other and equal-space.  Conditions for Irregular Reflection:  the reflecting surface should be rough.  The reflecting rays of light are not parallel to each other.

    Q 4. What are the laws of reflection of Light?

    Ans: A ray of light obeys the following laws of reflection:  The angle of incidence is equal to the angle of reflection.  the incident ray, the reflected ray, and the normal at the point of incidence, all lie in the same plane.

    Q 5. Define the following terms: (i) Incident ray (ii) reflected ray (iii) normal (iv) angle of Incidence (v) angle of reflection (vi) Ray of light (vii) beam of light.

    Ans: Incident Ray: The ray of light coming from a source of light is known as an incident ray. Reflected Ray: the light ray which is thrown back, when the incident ray hits the reflecting surface. Normal: A line (imaginary) at the right angle to the plane (surface) is called normal to the surface. The angle of incidence: the angle between the incident ray and the normal. Ray of light: the direction of path taken by light is known as ray of light Beam of light: a beam is a stream of light energy.

    Q 6. What are the spherical mirrors? How light is reflected from spherical mirrors? Give the uses of spherical mirrors.

    Ans: A Spherical mirror is a portion of the reflecting surface of a hollow sphere. Spherical mirrors are of two types:  Concave Mirror: The mirror whose inner curved surface is reflecting is called the concave mirror.  Convex Mirror: The mirror whose outer curved surface is reflecting is called the convex mirror.

    Q 7. Write down the Uses of spherical mirrors.

    Ans: nowadays spherical mirrors have a large number of scientific and practical uses. A few uses are given below: • Doctors use concave mirrors for examination of the ear, nose, throat, and eyes. • Concave mirrors with a parabolic shape are used in searchlights to throw an intense beam of light to a large distance. • Some people use a concave minor for shaving because when a man stands between the principal focus and pole of a concave mirror, he sees an enlarged, erect, and virtual image of his face. This is the reason why a concave mirror of a large focal length is used for shaving. • Concave mirrors are used to throw light on the slides of the microscope so that the slides can be viewed more clearly. • Nowadays developed countries use giant concave mirrors in their huge telescopes. • Convex mirrors are used in motorcycles and automobiles which enables the driver to see the automobiles coming behind him.

    Q 8. Define the center of curvature, Radius of curvature, aperture, pole, and principal axis.

    Ans: Center of Curvature: The center of the sphere, of which a concave mirror or convex mirror is a part is known as the Center of Curvature of the spherical mirror. Radius of Curvature: The radius of the sphere, of which a concave mirror or convex mirror is a part is known as the Radius of Curvature” of the spherical mirror. Aperture: The front section of a spherical mirror is circular and its diameter is known as the Aperture. Pole: The center of the concave or convex mirror is called the pole of the mirror. Principal Axis: A line joining the pole of the mirror and the center of curvature is called the “Principal Axis” of the mirror.

    Q 9. Define the principal focus for concave and convex mirrors and why they are called the real and virtual focus.

    Ans: Real Focus for Concave mirror: Rays of right parallel to the principal axis after reflection from a concave mirror converge to a point F. This point is called the “Principal focus” of the mirror. Since rays infect, and pass through this point, therefore, it is called real focus. Virtual Focus for Convex mirror: In the case of a convex mirror, rays parallel to the principal axis after reflection appear to come from a point F situated behind the mirror. This point is called the principal focus of the convex mirror. The principal focus of a convex minor is virtual because the reflected rays do not pass through it but appear to do so. Therefore, its focus is called virtual focus.

    Q 10. Define focal length and write down its relation with the radius of curvature.

    Ans: The distance between the pole and the principal focus of a spherical mirror (concave as well as convex) is called the “Focal Length”. It is denoted by f. Relation between Radius of curvature and focal length: The radius of curvature of a spherical minor is twice its focal length. i.e.

    Q 11. Define linear magnification.

    Ans: The ratio of the height of the image to that of the object is called linear magnification or simply magnification and is denoted by the letter m.

    Q 12. Why convex mirrors are fixed on blind turns on the roads in hill areas?

    Ans: Convex mirrors are fixed on blind turns on the road in hill areas because drivers from one side of the turn can see the automobiles coming from the other side of the mountain. So chances of accidents can be minimized.

    Q 13. Why concave mirrors are used for the examination of the nose, ear, throat, and eye?

    Ans: Concave mirrors are used for the examination of the nose, ear, throat, and eye to view a big and clear image of these organs.

    Q 14. Why concave mirror is used for makeup or shaving?

    Ans: Concave mirror is used for makeup or shaving because when a man/woman stands between the principal focus and pole of the concave mirror, he can see an enlarged image of his/her face. This is the reason why a concave mirror of a large focal length is used for shaving and make-up.

    Q 15. Explain with the help of activity whether the image is smaller or larger, erect or inverted, real or virtual in a convex mirror.

    Ans: Take a convex mirror or a well-polished spoon (using the outside of the spoon) and hold it in one hand and a pencil in the other hand with its tip in an upright position. Now look at the image in the mirror. The image is a convex mirror looks as • Appears smaller • Upright • Behind the mirror • Virtual Now an object moves closer to a convex mirror the image in a convex mirror looks as: • Moves closer to the mirror • Becomes larger • Upright • Stays virtual.

    Q 16. Define mirror formula/ mirror equation. Also, write signs of convention.

    Ans: Curved mirror formula is the relationship between object distance ‘p’ image distance ’q’ from the mirror and the focal length ‘f’ of the mirror. Mathematically it can be written as: 1 This equation is true for both types of concave and convex mirrors. But we have already seen that the image is formed sometimes in front of a curved mirror and sometimes behind it. This makes it necessary to have a sign’s convection so that we may distinguish between the two cases and obtain the correct answer when substituting in the formula. Explanation: showing the use of the two signs conventions in common use are given below: • All distances are measured from the pole of the mirror • Distances measured against the incident of light are positive. • Distances measured in the same direction as incident of light are positive.

    Q 17. Explain with the help of activity whether the image is smaller or larger, erect or inverted in a concave mirror.

    Ans: Take a concave mirror or a well-polished speed with a concave surface hold it in one hand and pencil it in the other hand with the tip in upright. The image formed by the concave mirror is • Real image • Inverted Bns: For all object positions outside the principal focus. But when the object is placed between focus and pole then the image is: • Virtual • Upright.

    Q 18. What do you know about mirage?

    Ans: In hot summer days, a reflection of motor cars is seen on the roads, and the image of an airo-plane is seen on the runway, infect there is no water on the runway. It is due to total internal reflection and this phenomenon is known as mirage.

    Q 19. Write down the Law of Refraction.

    Ans: The refraction of light takes place according to the following two laws: • The incident ray, the refracted ray, and the normal all lie in the same plane. • When a ray of light passes from one particular medium to another, the ratio of the sine of the angle of incidence (i) to the sine of the angle of refraction (r) 1s constant. This constant ratio is called the “Refractive Index” of the second medium concerning the first and it is denoted by the letter ‘n’. it can be mathematically written as: n = sin i sin r It is called Snell’s Law. A ray of light entering the second medium perpendicularly through the surface of separation shows no change of direction.

    Q 20. What is Snell’s law?

    Ans: When a ray of light passes from one particular medium to another, the ratio of the sine of the angle of incidence (i) to the sine of the angle of refraction (r) is constant. This constant ratio is called the ‘Refractive Index’ of the second medium concerning the first and it is denoted by the letter ‘n’. it is called Snell’s Law. Mathematically can be written as: Sinθ1 It is called Snell’s Law. A ray of light entering the second medium perpendicularly through the surface of separation shows no change of direction.

    Q 21. What is a refractive index? Write down the methods to calculate the refractive index.

    Ans: When a ray of light passes from one particular medium to another, the ratio of the sine of the angle of incidence (i) to the sine of the angle of refraction (r) is constant. This constant ratio is called the “Refractive Index” of the second medium concerning the first and it is denoted by the letter ‘n’. It can mathematically be written: Second method: the refractive index of a medium can also be calculated by dividing the speed of light in a vacuum by the speed of light in that medium. As the speed of light in a vacuum is almost equal to the speed of light in air. We use the speed of light in air instead of vacuum, while calculating the refractive index of a medium.

    Q 22. Explain when the light changes its path, when pass through two different mediums.

    Ans: During retraction, light bends towards normal as the light enters from a rate to a denser medium. • During retraction light bends away as light enters from the denser to rare medium. • The angel of incidence is greater than the angel of retraction. When light enters from a rate to a denser medium. • The angle of incidence is smaller than the angle of refraction when light enters from denser to rare medium. • if the light ray (incident ray) is along the normal (i.e. 90°) to the interface between the two mediums, the ray passes through without deviation. • No refraction takes place in the same medium.

    Q 23. Define total internal reflection. What is meant by critical angle? Explain total internal reflection and the conditions necessary for it.

    Ans: “When a ray of light front a denser medium enters a rarer medium in such a way that the angle of incidence is greater than the critical angle, then the ray is reflected inside and does not emerge out from the denser medium. This phenomenon is called total internal reflection”.

    Q 24. What is meant by critical angle?

    Ans: “The angle of incidence in the denser medium for which the corresponding angle of refraction is 90° in the rarer medium is called the critical angle. This angle of incidence is denoted by C.

    Q 25. Write Conditions for total internal reflection.

    Ans: The ray of light should travel from a denser medium to a rare medium. The angle of incidence should be greater than the critical angle.

    Q 26. What should be the angle of incidence for total internal reflection?

    Ans: The angle of incidence for total internal reflection should be greater than the critical angle.

    Q 27. What is a prism?

    Ans: Prism: Prism is a transparent body having three rectangular and two triangular surfaces. The angle of prism: the angle of the triangular surface opposite to its base is known as the ‘angle of Prism’.

    Q 28. What is meant by the dispersion of Light?

    Ans: The refraction of waves depends on their wavelength. Since the sunlight consists of different colors, the waves of different wavelengths, thus when it passes through a prism then the waves of different wavelengths deviate on different paths, due to this white light disperses in different colors, which is called dispersion. Solar spectrum: the band of colors that are seen after the dispersion of white light on the screen is called a solar spectrum.

    Q 29. Define critical angle.

    Ans: Critical Angle: Critical angle is the angle of incidences in the denser medium to which the corresponding angle of reflation in the rarer medium is 90°.

    Q 30. What is a reflecting prism?

    Ans: A reflecting prism has one of its angles equal to 90° and each of the remaining two angles equal to 45°.

    Q 31. What is meant by Angle of Deviation?

    Ans: The angle between the original path of the incident ray and the path of refracted rya through a prism is known as the angle of deviation. It is represented by D.

    Q 32. Define lenses.

    Ans: A transparent body has two surfaces of which at least one is curved. OR Lens is a piece of transparent medium bounded by two surfaces at least one of which is curved.

    Q 33. How many types of lenses? Describe briefly.

    Ans: Lenses are classified into two categories. 1) Convex or Converging Lens: The lens that converges all parallel incident rays after refraction is called a convex or converging lens. OR The lens is thicker at the middle and thinner at the edges. 2) Concave or Diverging Lens: “The lens which diverges the light at the point from all incident parallel rays.

    Q 34. Define the power of the lens and its unit.

    Ans: If the focal length of a lens is f then its reciprocal 1 f is called the power of the lens. Diopter: The unit of power “Diopter” is defined as the power of a lens with a focal length of one meter. Its symbol is ‘D’. Positive Power: Because the focal length of a convex lens is positive, therefore the power of a lens is also positive. Negative Power: Whereas the focal length of a concave lens is negative therefore the power of a concave lens is negative. Opticians and eye specialists refer to the power of a lens instead of its focal length for their patients.

    Q 35. Which lens has greater power, the lens of less focal length or off greater focal length?

    Ans: The power of a lens is given by the formula: p = l/f Where “f” is the focal length in meters. Hence for a lens of large power, the focal length will be small.

    Q 36. To get a greater and clearer Image at what distance lens should be placed from the object?

    Ans: To get a greater and clearer image, the object should be placed within the principal focus of the lens so that a clear, enlarged, and erected image is obtained.

    Q 37. How image formation from a convex lens can be explained?

    Ans: Image formation in a convex lens can be explained with three rays. 1) The ray parallel to the principal axis passes through the focal point after refraction by the lens. 2) The ray passing through the optical center passes straight through the lens and passes undeviated. 3) The ray passing through the focal point becomes parallel to the principal axis after refraction by the lens.

    Q 38. When an object is beyond 2F forms a converging lens, which type of image is formed?

    Ans: When an object is beyond 2F from the converging lens, the image is between F and 2F, real, inverted, and smaller than the object.

    Q 39. When an object is present at 2F which type of image is formed in the case of the convex lens?

    Ans: The image is at 2F real inverted and of the same size as the object in the case of a convex lens.

    Q 40. When an object is present between lens and f then what is the nature of the image formed by a convex lens?

    Ans: When an object is between lens and F the image is formed behind the object, virtual, erect, and larger than the object in the case of a convex lens.

    Q 41. What is meant by lens formula?

    Ans: The relation between the object and image distance from the lens in terms of the focal length of the lens is called the lens.

    Q 42. What do you know about periscope?

    Ans: A Periscope is a long tube at the two ends of which are adjusted two reflecting prisms. The rays of light from an object are reflected through an angle of 900 by each prism. Thus light from a viewed object enters the observer’s eye. Periscope is normally used in tanks and submarines. With the help of a periscope, the commander of the submarine sitting in his cabin can see the surface of the sea. Similarly, a soldier sitting inside a tank can see the objects outside the tank.

    Q 43. How the power is lost in optical fiber through dispersion? Explain.

    Ans: When a light signal travels along fibers by multiple refractions, some of the light is absorbed by the impurities in the glass. Some of it is scattered by the group of atoms formed at places such as joints when fibers are joined together. Note: Careful manufacturing can reduce power loss by scaling and absorption.

    Q 44. What do you understand from Linear and Angular Magnification?

    Ans: Linear Magnification: “The ratio of the size of the image to the size of the object is called linear magnification.” Angular Magnification: “The ratio of the angle subtended by the image as seen through the device to that subtended by the object at the unaided eye is known as angular magnification”.

    Q 45. What do you know about a totally reflecting prism? Also, write its uses.

    Ans: A transparent body, whose three sides are rectangular and two sides are right-angled triangular is called a reflecting prism. Reflecting prism: A prism that has one angle of 90° is called a reflecting prism. Principal of totally reflecting prism: The total reflecting prism works on the principle of total internal reflection. The reflecting prism reflects a beam of light through 90° or 180°. One angle of the right angle and the other two 45° each. When light falls perpendicular to one side it enters the prism without deviation. These light rays strike with the hypogynous of the prism. The hypotenuse at the angle of 45°. This angle is greater than the critical angle of glass which is 42°. So the angle of incidence is greater than the critical angle the lights reflect through a prism at an angle of 90°. Uses of totally reflecting prism: • The reflecting prism is used in periscope. • It is used in binoculars. • it is used in textile engineering for designing. • It is used in projectors.

    Q 46. How the light signal is transmitted through optical fiber?

    Ans: The light signal is transmitted through the optical fiber in the form of 1 and 0. The digit 1 represents the presence of light while the digit 0 represents the absence of light. Note: usually the light signal is produced by “Laser” or “LED” which travels through the optical fiber.

    Q 47. What is a simple microscope?

    Ans: A magnifying glass is a convex lens that is used to produce magnified images of small objects. Hence it is called a simple microscope.

    Q 48. What is meant by resolving the power of the instrument?

    Ans: The resolving power of an instrument is the ability to distinguish between two closely placed objects of point sources.

    Q 49. What is a magnifying glass?

    Ans: Magnifying glass is a lens that forms a virtual image that is larger than the object and appears behind the lens.

    Q 50. What is a compound microscope? Also, write its three features.

    Ans: A compound microscope has two converging sets of lenses, the objective, and the eyepiece, and is used to investigate the structure of small objects. Three main Features are as • It gives greater magnification than a single lens. • The objective lens has a short focal length, f < 1 cm. • The eyepiece has a focal length, fe Of a few cm.

    Q 51. Which formula is used to determine the magnification of a compound microscope?

    Ans: The magnification of the compound microscope.

    Q 52. Write uses of a compound microscope.

    Ans: A compound microscope is used to study bacteria and other micro-objects. It is also used for research in several fields of science like Microbiology, Botany, Geology, and Genetics.

    Q 53. Why would it be advantageous to us when blue light is used with a compound microscope?

    Ans: The blue light of short wavelength produces less diffraction increases its resolving power. Hence, it allows more details to be seen.

    Q 54. What is the least distance of distinct vision? How it is affected by the increase in age?

    Ans: The minimum distance of an object from the eye at which it produces a sharp image on the eye is called the least distance of a distinct or near point. Its volume is normally 25 cm with the increase in age, its value usually increases.

    Q 55. Why objective of a short focal length is preferred in a microscope?

    Ans: The magnification of the microscope. It is a chair from the above equation that M α 1 for i.e. smaller to focal length of objective greater will be its magnifying power and vice versa. Therefore, to increase the magnification power the value of the focal length of the objective must be smaller.

    Q 56. Define telescope. What do you know about refracting telescopes?

    Ans: Telescope is an optical instrument that is used to observe distant objects using lenses or mirrors. A telescope that uses two converging lenses is called a refracting telescope.

    Q 57. How terrestrial telescope is different from a telescope?

    Ans: The terrestrial telescope has an extra lens between the objective and the eyepiece.

    Q 58. What is a magnification of a refracting telescope?

    Ans: Magnification of refracting telescope can be determined by using the formula:

    Q 59. Which human organ works like the camera?

    Ans: The human eye works like a camera.

    Q 60. What is a pupil?

    Ans: Iris has an opening at its center called the pupil.

    Q 61. What is meant by a defect of vision? What are its types?

    Ans: The inability of the eye to see the image of objects is called a defect of vision. The defects of vision are: • Nearsightedness (Myopia) • Farsightedness(Hypermetropia).

    Q 62. What is the reason for short-sightedness? How It is corrected?

    Ans: Shortsightedness is due to the eyeball being too long. Light rays from a distant object are focused in front of the retina and a blurred image is produced. It is corrected by using, a diverging lens.

    Q 63. What is meant by hyper-metropia? How is it corrected?

    Ans: The disability of the eye to form distinct images of nearby objects on its retina is known as farsightedness or hypermetropia. This defect can be corrected with the aid of a suitable converging lens.

    Q 64. What are the near and far points of the normal eye?

    Ans: Near Point: A normal eye can see near objects clearly at a distance of about 25cm from the eye. This is near the point of the normal eye. Far Point: A normal eye can see far-off objects. So we can say that the far point of a normal eye will be at an infinite distance.

    Q 65. Which lens is used for the long-sightedness?

    Ans: Long-sightedness is corrected by wearing spectacles having a convex lens of such focal length which forms a virtual image of the object placed at normal 25 cm, at the near point O of the eye. Hence a clear image of the object is formed on the retina.

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    These 10th class physics notes were prepared according to the syllabus of all Punjab boards. Boards other than Punjab do not follow class 10 physics notes. These Punjab boards are Gujranwala Board, Lahore Board, Faisalabad Board, Multan Board, Rawalpindi Board, Bahawalpur Sargodha Board, DG Khan Board, Sahiwal.

    Finally, we tried our best to make these notes useful for you. But if you find any errors, however, any suggestions for its further accuracy are invited. And if you find that our efforts help you, share it with your mates because “Sharing is caring”.

  • 10th Class Physics Chapter 11: Sound

    10th Class Chapter 11: Sound Short and Simple Question & Answer

    In this post, you will find solved notes of 10th class physics chapter 11 in PDF. There are no obscure words in these notes, they are simple and well organized. You can download these notes by clicking on the download button at the bottom of this page. View or download these Physics Chapter 11 Audio Notes for Class 10 English Medium. Many students have successfully used the Physics Estimate Paper 2024 by Faiz Ul Islam to achieve good results in their exams.

    Q 1. What is reflection?

    Ans: Reflection of Light: When light traveling in a certain medium falls on the surface of another medium, a part of it turns back in the same medium. This is called the reflection of light. OR The bouncing back of light in the first medium after striking with any reflecting surface.

    Q 2. Define regular reflection and Irregular reflection.

    Ans: Regular Reflection: The reflection by a smooth surface in which all the reflected rays are parallel to each other is called regular reflection. Irregular Reflection: The reflection of light rays is not parallel to each other.

    Q 3. Write the conditions for regular and irregular reflection.

    Ans: Conditions for Regular Reflection:  The reflecting surface should be a plane surface.  The reflecting surface should be flat.  The reflected rays of light should be parallel to each other and equal-space.  Conditions for Irregular Reflection:  the reflecting surface should be rough.  The reflecting rays of light are not parallel to each other.

    Q 4. What are the laws of reflection of Light?

    Ans: A ray of light obeys the following laws of reflection:  The angle of incidence is equal to the angle of reflection.  the incident ray, the reflected ray, and the normal at the point of incidence, all lie in the same plane.

    Q 5. Define the following terms: (i) Incident ray (ii) reflected ray (iii) normal (iv) angle of Incidence (v) angle of reflection (vi) Ray of light (vii) beam of light.

    Ans: Incident Ray: The ray of light coming from a source of light is known as an incident ray. Reflected Ray: the light ray which is thrown back, when the incident ray hits the reflecting surface. Normal: A line (imaginary) at the right angle to the plane (surface) is called normal to the surface. The angle of incidence: the angle between the incident ray and the normal. Ray of light: the direction of path taken by light is known as ray of light Beam of light: a beam is a stream of light energy.

    Q 6. What are the spherical mirrors? How light is reflected from spherical mirrors? Give the uses of spherical mirrors.

    Ans: A Spherical mirror is a portion of the reflecting surface of a hollow sphere. Spherical mirrors are of two types:  Concave Mirror: The mirror whose inner curved surface is reflecting is called the concave mirror.  Convex Mirror: The mirror whose outer curved surface is reflecting is called the convex mirror.

    Q 7. Write down the Uses of spherical mirrors.

    Ans: nowadays spherical mirrors have a large number of scientific and practical uses. A few uses are given below: • Doctors use concave mirrors for examination of the ear, nose, throat, and eyes. • Concave mirrors with a parabolic shape are used in searchlights to throw an intense beam of light to a large distance. • Some people use a concave minor for shaving because when a man stands between the principal focus and pole of a concave mirror, he sees an enlarged, erect, and virtual image of his face. This is the reason why a concave mirror of a large focal length is used for shaving. • Concave mirrors are used to throw light on the slides of the microscope so that the slides can be viewed more clearly. • Nowadays developed countries use giant concave mirrors in their huge telescopes. • Convex mirrors are used in motorcycles and automobiles which enables the driver to see the automobiles coming behind him.

    Q 8. Define the center of curvature, Radius of curvature, aperture, pole, and principal axis.

    Ans: Center of Curvature: The center of the sphere, of which a concave mirror or convex mirror is a part is known as the Center of Curvature of the spherical mirror. Radius of Curvature: The radius of the sphere, of which a concave mirror or convex mirror is a part is known as the Radius of Curvature” of the spherical mirror. Aperture: The front section of a spherical mirror is circular and its diameter is known as the Aperture. Pole: The center of the concave or convex mirror is called the pole of the mirror. Principal Axis: A line joining the pole of the mirror and the center of curvature is called the “Principal Axis” of the mirror.

    Q 9. Define the principal focus for concave and convex mirrors and why they are called the real and virtual focus.

    Ans: Real Focus for Concave mirror: Rays of right parallel to the principal axis after reflection from a concave mirror converge to a point F. This point is called the “Principal focus” of the mirror. Since rays infect, and pass through this point, therefore, it is called real focus. Virtual Focus for Convex mirror: In the case of a convex mirror, rays parallel to the principal axis after reflection appear to come from a point F situated behind the mirror. This point is called the principal focus of the convex mirror. The principal focus of a convex minor is virtual because the reflected rays do not pass through it but appear to do so. Therefore, its focus is called virtual focus.

    Q 10. Define focal length and write down its relation with the radius of curvature.

    Ans: The distance between the pole and the principal focus of a spherical mirror (concave as well as convex) is called the “Focal Length”. It is denoted by f. Relation between Radius of curvature and focal length: The radius of curvature of a spherical minor is twice its focal length. i.e.

    Q 11. Define linear magnification.

    Ans: The ratio of the height of the image to that of the object is called linear magnification or simply magnification and is denoted by the letter m.

    Q 12. Why convex mirrors are fixed on blind turns on the roads in hill areas?

    Ans: Convex mirrors are fixed on blind turns on the road in hill areas because drivers from one side of the turn can see the automobiles coming from the other side of the mountain. So chances of accidents can be minimized.

    Q 13. Why concave mirrors are used for the examination of the nose, ear, throat, and eye?

    Ans: Concave mirrors are used for the examination of the nose, ear, throat, and eye to view a big and clear image of these organs.

    Q 14. Why concave mirror is used for makeup or shaving?

    Ans: Concave mirror is used for makeup or shaving because when a man/woman stands between the principal focus and pole of the concave mirror, he can see an enlarged image of his/her face. This is the reason why a concave mirror of a large focal length is used for shaving and make-up.

    Q 15. Explain with the help of activity whether the image is smaller or larger, erect or inverted, real or virtual in a convex mirror.

    Ans: Take a convex mirror or a well-polished spoon (using the outside of the spoon) and hold it in one hand and a pencil in the other hand with its tip in an upright position. Now look at the image in the mirror. The image is a convex mirror looks as • Appears smaller • Upright • Behind the mirror • Virtual Now an object moves closer to a convex mirror the image in a convex mirror looks as: • Moves closer to the mirror • Becomes larger • Upright • Stays virtual.

    Q 16. Define mirror formula/ mirror equation. Also, write signs of convention.

    Ans: Curved mirror formula is the relationship between object distance ‘p’ image distance ’q’ from the mirror and the focal length ‘f’ of the mirror. Mathematically it can be written as: 1 This equation is true for both types of concave and convex mirrors. But we have already seen that the image is formed sometimes in front of a curved mirror and sometimes behind it. This makes it necessary to have a sign’s convection so that we may distinguish between the two cases and obtain the correct answer when substituting in the formula. Explanation: showing the use of the two signs conventions in common use are given below: • All distances are measured from the pole of the mirror • Distances measured against the incident of light are positive. • Distances measured in the same direction as incident of light are positive.

    Q 17. Explain with the help of activity whether the image is smaller or larger, erect or inverted in a concave mirror.

    Ans: Take a concave mirror or a well-polished speed with a concave surface hold it in one hand and pencil it in the other hand with the tip in upright. The image formed by the concave mirror is • Real image • Inverted Bns: For all object positions outside the principal focus. But when the object is placed between focus and pole then the image is: • Virtual • Upright.

    Q 18. What do you know about mirage?

    Ans: In hot summer days, a reflection of motor cars is seen on the roads, and the image of an airo-plane is seen on the runway, infect there is no water on the runway. It is due to total internal reflection and this phenomenon is known as mirage.

    Q 19. Write down the Law of Refraction.

    Ans: The refraction of light takes place according to the following two laws: • The incident ray, the refracted ray, and the normal all lie in the same plane. • When a ray of light passes from one particular medium to another, the ratio of the sine of the angle of incidence (i) to the sine of the angle of refraction (r) 1s constant. This constant ratio is called the “Refractive Index” of the second medium concerning the first and it is denoted by the letter ‘n’. it can be mathematically written as: n = sin i sin r It is called Snell’s Law. A ray of light entering the second medium perpendicularly through the surface of separation shows no change of direction.

    Q 20. What is Snell’s law?

    Ans: When a ray of light passes from one particular medium to another, the ratio of the sine of the angle of incidence (i) to the sine of the angle of refraction (r) is constant. This constant ratio is called the ‘Refractive Index’ of the second medium concerning the first and it is denoted by the letter ‘n’. it is called Snell’s Law. Mathematically can be written as: Sinθ1 It is called Snell’s Law. A ray of light entering the second medium perpendicularly through the surface of separation shows no change of direction.

    Q 21. What is a refractive index? Write down the methods to calculate the refractive index.

    Ans: When a ray of light passes from one particular medium to another, the ratio of the sine of the angle of incidence (i) to the sine of the angle of refraction (r) is constant. This constant ratio is called the “Refractive Index” of the second medium concerning the first and it is denoted by the letter ‘n’. It can mathematically be written: Second method: the refractive index of a medium can also be calculated by dividing the speed of light in a vacuum by the speed of light in that medium. As the speed of light in a vacuum is almost equal to the speed of light in air. We use the speed of light in air instead of vacuum, while calculating the refractive index of a medium.

    Q 22. Explain when the light changes its path, when pass through two different mediums.

    Ans: During retraction, light bends towards normal as the light enters from a rate to a denser medium. • During retraction light bends away as light enters from the denser to rare medium. • The angel of incidence is greater than the angel of retraction. When light enters from a rate to a denser medium. • The angle of incidence is smaller than the angle of refraction when light enters from denser to rare medium. • if the light ray (incident ray) is along the normal (i.e. 90°) to the interface between the two mediums, the ray passes through without deviation. • No refraction takes place in the same medium.

    Q 23. Define total internal reflection. What is meant by critical angle? Explain total internal reflection and the conditions necessary for it.

    Ans: “When a ray of light front a denser medium enters a rarer medium in such a way that the angle of incidence is greater than the critical angle, then the ray is reflected inside and does not emerge out from the denser medium. This phenomenon is called total internal reflection”.

    Q 24. What is meant by critical angle?

    Ans: “The angle of incidence in the denser medium for which the corresponding angle of refraction is 90° in the rarer medium is called the critical angle. This angle of incidence is denoted by C.

    Q 25. Write Conditions for total internal reflection.

    Ans: The ray of light should travel from a denser medium to a rare medium. The angle of incidence should be greater than the critical angle.

    Q 26. What should be the angle of incidence for total internal reflection?

    Ans: The angle of incidence for total internal reflection should be greater than the critical angle.

    Q 27. What is a prism?

    Ans: Prism: Prism is a transparent body having three rectangular and two triangular surfaces. The angle of prism: the angle of the triangular surface opposite to its base is known as the ‘angle of Prism’.

    Q 28. What is meant by the dispersion of Light?

    Ans: The refraction of waves depends on their wavelength. Since the sunlight consists of different colors, the waves of different wavelengths, thus when it passes through a prism then the waves of different wavelengths deviate on different paths, due to this white light disperses in different colors, which is called dispersion. Solar spectrum: the band of colors that are seen after the dispersion of white light on the screen is called a solar spectrum.

    Q 29. Define critical angle.

    Ans: Critical Angle: Critical angle is the angle of incidences in the denser medium to which the corresponding angle of reflation in the rarer medium is 90°.

    Q 30. What is a reflecting prism?

    Ans: A reflecting prism has one of its angles equal to 90° and each of the remaining two angles equal to 45°.

    Q 31. What is meant by Angle of Deviation?

    Ans: The angle between the original path of the incident ray and the path of refracted rya through a prism is known as the angle of deviation. It is represented by D.

    Q 32. Define lenses.

    Ans: A transparent body has two surfaces of which at least one is curved. OR Lens is a piece of transparent medium bounded by two surfaces at least one of which is curved.

    Q 33. How many types of lenses? Describe briefly.

    Ans: Lenses are classified into two categories. 1) Convex or Converging Lens: The lens that converges all parallel incident rays after refraction is called a convex or converging lens. OR The lens is thicker at the middle and thinner at the edges. 2) Concave or Diverging Lens: “The lens which diverges the light at the point from all incident parallel rays.

    Q 34. Define the power of the lens and its unit.

    Ans: If the focal length of a lens is f then its reciprocal 1 f is called the power of the lens. Diopter: The unit of power “Diopter” is defined as the power of a lens with a focal length of one meter. Its symbol is ‘D’. Positive Power: Because the focal length of a convex lens is positive, therefore the power of a lens is also positive. Negative Power: Whereas the focal length of a concave lens is negative therefore the power of a concave lens is negative. Opticians and eye specialists refer to the power of a lens instead of its focal length for their patients.

    Q 35. Which lens has greater power, the lens of less focal length or off greater focal length?

    Ans: The power of a lens is given by the formula: p = l/f Where “f” is the focal length in meters. Hence for a lens of large power, the focal length will be small.

    Q 36. To get a greater and clearer Image at what distance lens should be placed from the object?

    Ans: To get a greater and clearer image, the object should be placed within the principal focus of the lens so that a clear, enlarged, and erected image is obtained.

    Q 37. How image formation from a convex lens can be explained?

    Ans: Image formation in a convex lens can be explained with three rays. 1) The ray parallel to the principal axis passes through the focal point after refraction by the lens. 2) The ray passing through the optical center passes straight through the lens and passes undeviated. 3) The ray passing through the focal point becomes parallel to the principal axis after refraction by the lens.

    Q 38. When an object is beyond 2F forms a converging lens, which type of image is formed?

    Ans: When an object is beyond 2F from the converging lens, the image is between F and 2F, real, inverted, and smaller than the object.

    Q 39. When an object is present at 2F which type of image is formed in the case of the convex lens?

    Ans: The image is at 2F real inverted and of the same size as the object in the case of a convex lens.

    Q 40. When an object is present between lens and f then what is the nature of the image formed by a convex lens?

    Ans: When an object is between lens and F the image is formed behind the object, virtual, erect, and larger than the object in the case of a convex lens.

    Q 41. What is meant by lens formula?

    Ans: The relation between the object and image distance from the lens in terms of the focal length of the lens is called the lens.

    Q 42. What do you know about periscope?

    Ans: A Periscope is a long tube at the two ends of which are adjusted two reflecting prisms. The rays of light from an object are reflected through an angle of 900 by each prism. Thus light from a viewed object enters the observer’s eye. Periscope is normally used in tanks and submarines. With the help of a periscope, the commander of the submarine sitting in his cabin can see the surface of the sea. Similarly, a soldier sitting inside a tank can see the objects outside the tank.

    Q 43. How the power is lost in optical fiber through dispersion? Explain.

    Ans: When a light signal travels along fibers by multiple refractions, some of the light is absorbed by the impurities in the glass. Some of it is scattered by the group of atoms formed at places such as joints when fibers are joined together. Note: Careful manufacturing can reduce power loss by scaling and absorption.

    Q 44. What do you understand from Linear and Angular Magnification?

    Ans: Linear Magnification: “The ratio of the size of the image to the size of the object is called linear magnification.” Angular Magnification: “The ratio of the angle subtended by the image as seen through the device to that subtended by the object at the unaided eye is known as angular magnification”.

    Q 45. What do you know about a totally reflecting prism? Also, write its uses.

    Ans: A transparent body, whose three sides are rectangular and two sides are right-angled triangular is called a reflecting prism. Reflecting prism: A prism that has one angle of 90° is called a reflecting prism. Principal of totally reflecting prism: The total reflecting prism works on the principle of total internal reflection. The reflecting prism reflects a beam of light through 90° or 180°. One angle of the right angle and the other two 45° each. When light falls perpendicular to one side it enters the prism without deviation. These light rays strike with the hypogynous of the prism. The hypotenuse at the angle of 45°. This angle is greater than the critical angle of glass which is 42°. So the angle of incidence is greater than the critical angle the lights reflect through a prism at an angle of 90°. Uses of totally reflecting prism: • The reflecting prism is used in periscope. • It is used in binoculars. • it is used in textile engineering for designing. • It is used in projectors.

    Q 46. How the light signal is transmitted through optical fiber?

    Ans: The light signal is transmitted through the optical fiber in the form of 1 and 0. The digit 1 represents the presence of light while the digit 0 represents the absence of light. Note: usually the light signal is produced by “Laser” or “LED” which travels through the optical fiber.

    Q 47. What is a simple microscope?

    Ans: A magnifying glass is a convex lens that is used to produce magnified images of small objects. Hence it is called a simple microscope.

    Q 48. What is meant by resolving the power of the instrument?

    Ans: The resolving power of an instrument is the ability to distinguish between two closely placed objects of point sources.

    Q 49. What is a magnifying glass?

    Ans: Magnifying glass is a lens that forms a virtual image that is larger than the object and appears behind the lens.

    Q 50. What is a compound microscope? Also, write its three features.

    Ans: A compound microscope has two converging sets of lenses, the objective, and the eyepiece, and is used to investigate the structure of small objects. Three main Features are as • It gives greater magnification than a single lens. • The objective lens has a short focal length, f < 1 cm. • The eyepiece has a focal length, fe Of a few cm.

    Q 51. Which formula is used to determine the magnification of a compound microscope?

    Ans: The magnification of the compound microscope.

    Q 52. Write uses of a compound microscope.

    Ans: A compound microscope is used to study bacteria and other micro-objects. It is also used for research in several fields of science like Microbiology, Botany, Geology, and Genetics.

    Q 53. Why would it be advantageous to us when blue light is used with a compound microscope?

    Ans: The blue light of short wavelength produces less diffraction increases its resolving power. Hence, it allows more details to be seen.

    Q 54. What is the least distance of distinct vision? How it is affected by the increase in age?

    Ans: The minimum distance of an object from the eye at which it produces a sharp image on the eye is called the least distance of a distinct or near point. Its volume is normally 25 cm with the increase in age, its value usually increases.

    Q 55. Why objective of a short focal length is preferred in a microscope?

    Ans: The magnification of the microscope. It is a chair from the above equation that M α 1 for i.e. smaller to focal length of objective greater will be its magnifying power and vice versa. Therefore, to increase the magnification power the value of the focal length of the objective must be smaller.

    Q 56. Define telescope. What do you know about refracting telescopes?

    Ans: Telescope is an optical instrument that is used to observe distant objects using lenses or mirrors. A telescope that uses two converging lenses is called a refracting telescope.

    Q 57. How terrestrial telescope is different from a telescope?

    Ans: The terrestrial telescope has an extra lens between the objective and the eyepiece.

    Q 58. What is a magnification of a refracting telescope?

    Ans: Magnification of refracting telescope can be determined by using the formula:

    Q 59. Which human organ works like the camera?

    Ans: The human eye works like a camera.

    Q 60. What is a pupil?

    Ans: Iris has an opening at its center called the pupil.

    Q 61. What is meant by a defect of vision? What are its types?

    Ans: The inability of the eye to see the image of objects is called a defect of vision. The defects of vision are: • Nearsightedness (Myopia) • Farsightedness(Hypermetropia).

    Q 62. What is the reason for short-sightedness? How It is corrected?

    Ans: Shortsightedness is due to the eyeball being too long. Light rays from a distant object are focused in front of the retina and a blurred image is produced. It is corrected by using, a diverging lens.

    Q 63. What is meant by hyper-metropia? How is it corrected?

    Ans: The disability of the eye to form distinct images of nearby objects on its retina is known as farsightedness or hypermetropia. This defect can be corrected with the aid of a suitable converging lens.

    Q 64. What are the near and far points of the normal eye?

    Ans: Near Point: A normal eye can see near objects clearly at a distance of about 25cm from the eye. This is near the point of the normal eye. Far Point: A normal eye can see far-off objects. So we can say that the far point of a normal eye will be at an infinite distance.

    Q 65. Which lens is used for the long-sightedness?

    Ans: Long-sightedness is corrected by wearing spectacles having a convex lens of such focal length which forms a virtual image of the object placed at normal 25 cm, at the near point O of the eye. Hence a clear image of the object is formed on the retina.

    Download PDF Format

    Like our Facebook page for  education Faizul Islam Updates.

    These 10th class physics notes were prepared according to the syllabus of all Punjab boards. Boards other than Punjab do not follow class 10 physics notes. These Punjab boards are Gujranwala Board, Lahore Board, Faisalabad Board, Multan Board, Rawalpindi Board, Bahawalpur Sargodha Board, DG Khan Board, Sahiwal.

    Finally, we tried our best to make these notes useful for you. But if you find any errors, however, any suggestions for its further accuracy are invited. And if you find that our efforts help you, share it with your mates because “Sharing is caring”.

  • 10th Class Physics Chapter 10: Simple Harmonic Motion and Waves

    10th Class Chapter 11: Simple Harmonic Motion and Waves Short and Simple Question & Answer

    In this post, you will find solved notes of 10th class physics chapter 11 in PDF. There are no obscure words in these notes, they are simple and well organized. You can download these notes by clicking on the download button at the bottom of this page. View or download these Physics Chapter 11 Audio Notes for Class 10 English Medium. Many students have successfully used the Physics Estimate Paper 2024 by Faiz Ul Islam to achieve good results in their exams.

    Q 1. What is meant by oscillation?

    Ans: A body moving back and forth or to and fro about its mean position is called vibration or oscillation. Examples: Motion of the simple pendulum

    Q 2. Define Simple Harmonic Motion.

    Ans: The acceleration of a body executing SHM is directly proportional to the displacement of the body from the mean position and is always directed toward the mean position. Mathematically: a = √−x Where a is acceleration x is displacement from the mean position.

    Q 3. Define Hooke’s Law. Give its expression.

    Ans: according to Hooke’s law the exerted force is directly proportional to change in length. F ∝ X

    Q 4. How does the stiffness of the spring affect the value of k?

    Ans: The value of k is a measure of the stiffness of the spring. Stiff springs have large k values and soft springs have small k values.

    Q 5. What is the function of restoring force during oscillatory motion?

    Ans: A restoring force always pushes or pulls the object performing oscillatory motion towards the mean position. Fr = kx

    Q 6. Which type of forces are acting on a displaced pendulum

    Ans: The restoring force that causes the pendulum to undergo simple harmonic motion is the component of gravitational force mg sinθ tangent to the path of motion

    Q 7. Define period and write down the formula of Period for mass attached to a spring and for a simple pendulum.

    Ans: Period (T): The time required to complete one vibration is called period. It is donated by “T” i. The period T of the simple harmonic motion of a mass m attached to a spring is given by the equation

    Q 8. Define the following terms which characterize simple harmonic motion.

    Ans: Vibration: One Complete round trip of a vibrating body about its mean position is called one vibration. Period (T): The time taken by a vibrating body to complete the vibration is called period. Frequency (f): The number of vibrations per cycle of a vibrating body in one second is called its frequency. It is reciprocal of period i.e. f = 1/T. Amplitude (A): the displacement of a vibrating body on either side from its mean position to its extreme position is called its amplitude. Displacement (D): Distance covered by the vibrating body at any instant during the vibration from the mean position.

    Q 9. Write down important features of simple Harmonic Motion.

    Ans: Important features of SHM are summarized as 1. A body executing SHM always vibrates about a fixed position. 2. Its acceleration is always directed towards the mean position 3. The magnitude of acceleration is always directly proportional to its displacement from the mean position i.e. acceleration will be zero at the mean position while it will be maximum at the extreme positions. 4. Its velocity is maximum at the mean position and zero at the extreme positions.

    Q 10. Differentiate between mechanical waves and electromagnetic waves.

    Ans: Mechanical waves: The Waves which require a material medium for their propagation are known as mechanical waves. Examples: Sound waves, Waves produced on a rope, water waves Electromagnetic waves: the waves that can propagate with or without material medium are known as electromagnetic waves. Example: X-rays, Radio waves, Heat, and light waves

    Q 11. Differentiate between transverse waves and compressional or longitudinal waves.

    Ans: Transverse Waves: The waves in which the direction of vibratory motion of particles of medium is perpendicular to the direction of propagation of waves are called transverse waves. Example: Waves produced in a rope, Water Waves Compressional / Longitudinal Waves: The Waves in which the direction of vibratory motion of particles of medium is parallel to the direction of propagation of waves are called compressional or longitudinal waves Examples: Sound waves

    Q 12. Write down the relationship between frequency and period.

    Ans: Frequency is a reciprocal of period i.e. they have an inverse relationship

    Q 13. When the ball is at the center of the bowl what will be the net force?

    Ans: When the ball is at the center of the bowl the net force acting on the ball is zero because at this position weight of the ball acts downward and is equal to the upward normal force of the surface of the bowl.

    Q 14. What is the displacement of an object in a simple harmonic motion when kinetic and potential energy are equal?

    Ans: Kinetic energy and potential energy are equal when the body is in the middle of the mean and extreme position.

    Q 15. If we replace the iron bob of the dimple pendulum with the wooden bob what will be the effect of a period of the simple pendulum?

    Ans: The period of a simple pendulum would remain the same because the period of a pendulum is independent of mass and amplitude.

    Q 16. What is meant by damped oscillation?

    Ans: The oscillations of a system in the presence of some resistive force are damped.

    Q 17. How does the mechanical energy of the system reduce?

    Ans: The friction reduces the mechanical energy of the system as time passes and the motion is said to be damped. This damped progressively reduces the amplitude of the motion.

    Q 18. Explain the function of the shock absorber (application of the damped oscillation)

    Ans: Shock observers: shock absorbers are one practical application of damped motion. A shock absorber consists of a piston moving through a liquid such as oil. The upper part of the shock absorber is firmly attached to the body of the car. When the car travels over a bump on the road, the car may vibrate violently. The shock absorbers damp these vibrations and convert their energy into the heat energy of the oil.

    Q 19. How a wave can be defined? In which categories are these divided?

    Ans: A wave is a disturbance in the medium that causes the particles of the medium to undergo vibratory motion about their mean position in equal intervals of time. There are two categories of waves:  Mechanical waves  Electromagnetic waves

    Q 20. Define electromagnetic waves and give examples.

    Ans: Electromagnetic waves: the waves that do not require any medium for their propagation are called electromagnetic waves. Example: X-rays, Radio waves, Heat, and light waves

    Q 21. Define mechanical waves, and give examples.

    Ans: Waves that require any medium for their propagation are called mechanical waves Examples: Water Wave, Sound Waves, etc.

    Q 22. Do the mechanical waves pass through a space?

    Ans: No, mechanical waves do not pass through space because they require a medium for their propagation.

    Q 23. Define longitudinal or compressional waves

    Ans: The waves in which the particles of the medium move back and forth along the direction of the propagation of the wave are called longitudinal or compressional waves. Examples: Sound Waves

    Q 24. Differentiate between Crest and Trough?

    Ans: Crest the highest point on the wave is called the crest Trough: The lowest point on the wave is called the trough.

    Q 25. Define transverse waves.

    Ans: Transverse waves: the wave in which the particle of medium moves perpendicular or the direction for propagation of the wave. Example: Water waves, Light waves, Waves produced on a string or spring

    Q 26. What is a wave equation?

    Ans: The relationship between the velocity, frequency, and wavelength of the wave is known as the wave equation. i.e v = λ f

    Q 27. How energy can be transferred from one place to another?

    Ans: Energy can be transferred from one place to another through waves.

    Q 28. Describe types of mechanical waves.

    Ans: Longitudinal waves/ compressional waves: in longitudinal waves the particles of the medium move back and forth along the direction of propagation of the wave. Example: Sound waves Transverse Waves: the waves in which the motion of particles of the medium is perpendicular to the motion of the wave Example: waves on the surface of water and light waves are also transverse waves.

    Q 29. Why height lines are seen on the screen of the ripple tank?

    Ans: The crest of the waves appears as bright lines on the paper because they behave like a convex lens and converge the rays of light falling on them. So, bright lines are seen on the screen of the ripple tank.

    Q 30. Why dark lines are seen on the screen of the ripple tank?

    Ans: The troughs of the waves appear as dark lines on the paper because they behave like a concave lens and diverge the rays of light falling on them. So, dark lines are seen on the screen of the ripple tank.

    Q 31. How can we generate circular waves in a ripple tank?

    Ans: We can generate circular waves in a ripple tank by attaching a knob on the lower side of the vibrating bar. Now it is lowered in such a way that knob touches the water surface. When the vibrator is set on, circular waves are produced on the water’s surface.

    Q 32. About v = λ f which two quantities depend upon the properties of the medium and why does the third one not?

    Ans: In the given relation v and λ depend on the properties of the medium while f does not depend on the properties of the medium because f depends upon the frequency of the vibrator.

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    These 10th class physics notes were prepared according to the syllabus of all Punjab boards. Boards other than Punjab do not follow class 10 physics notes. These Punjab boards are Gujranwala Board, Lahore Board, Faisalabad Board, Multan Board, Rawalpindi Board, Bahawalpur Sargodha Board, DG Khan Board, Sahiwal.

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