Light

Physics, SSC-Punjab Class 10. This chapter is split into 65 topics and has 1,524 practice questions. The topics covered are listed below, followed by 10 free sample questions from the chapter.

Topics in this chapter

1. Derivation of n = 1/sin C 23 questions
2. Structure of an Optical Fibre 24 questions
3. Speed and Travel Time of Light in Media 23 questions
4. Laws of Reflection 21 questions
5. Working of an Optical Fibre 23 questions
6. Short Answer Items and Common Misconceptions 30 questions
7. Image Height from Magnification 24 questions
8. Mirror Formula Numericals 24 questions
9. Lens Formula Numericals Real Images 24 questions
10. Power of a Lens 20 questions
11. Speed of Light and Critical Angle Data 24 questions
12. Image Nature from Object Distance and Focal Length 24 questions
13. Spectacle Lens Calculations for Eye Defects 24 questions
14. Types of Lenses 24 questions
15. Snell's Law Numericals Finding the Angle of Refraction 24 questions
16. Snell's Law Numericals Finding the Angle of Incidence 24 questions
17. Total Internal Reflection 21 questions
18. Bending of Light Towards or Away from the Normal 23 questions
19. Lens Formula Numericals Finding the Focal Length 24 questions
20. Critical Angle Numericals from Refractive Index 24 questions
21. Concave and Convex Mirrors and Sign Convention 20 questions
22. Acoustic Lenses 21 questions
23. Image Formation in the Eye and Myopia 30 questions
24. Refractive Index from the Critical Angle 24 questions
25. Reflection of Light Basics 25 questions
26. Linear Magnification 20 questions
27. Refractive Index from Speed of Light 24 questions
28. Critical Angle Between Two Media 24 questions
29. Lens Formula Numericals Finding the Object Distance 24 questions
30. Convex and Concave Mirror Image Calculations 24 questions
31. Linear Magnification Numericals 20 questions
32. Lens and Mirror Formula 20 questions
33. Long-sightedness (Hypermetropia) 20 questions
34. Plane Mirror Distance Numericals 25 questions
35. Advantages of Optical Fibres 24 questions
36. Ray Diagram Rules for a Convex Lens 20 questions
37. Image Formation by a Convex Lens for Different Object Positions 20 questions
38. Lens Formula Numericals Virtual Images 24 questions
39. Experiment on Total Internal Reflection 20 questions
40. Gravitational Lensing 22 questions
41. Lateral Inversion 22 questions
42. Light Multiple Choice Practice 22 questions
43. Normal and Angles of Incidence and Reflection 23 questions
44. Visible Spectrum and Colours of Light 23 questions
45. Optical Fibre Critical Angle Calculations 24 questions
46. Power of Lens Numericals 26 questions
47. Critical Angle 20 questions
48. Refractive Index Concept 23 questions
49. Image Distance and Height Numericals 24 questions
50. The Photographic Enlarger 20 questions
51. Dispersion and Infrared Radiation 30 questions
52. Speed of Light in a Medium from Refractive Index 24 questions
53. The Slide Projector 21 questions
54. Snell's Law Numericals Finding the Refractive Index 24 questions
55. Reflection Angle Numericals 25 questions
56. Locating the Plane Mirror Image 20 questions
57. Refractive Index Values of Common Media 24 questions
58. Lens Terms and Action on Parallel Rays 30 questions
59. Mirror Magnification and Image Height 24 questions
60. Real and Virtual Images 20 questions
61. Laws of Refraction and Snell's Law 23 questions
62. Image Formed by a Plane Mirror 22 questions
63. Everyday Effects and Basics of Refraction 30 questions
64. Refraction Through Blocks and Prisms 30 questions
65. The Magnifying Glass and the Camera 27 questions

Sample questions: Light

10 sample questions with the correct answer and an explanation. Try to answer each one before reading the explanation.

Q1. Each ray falling on a rough sheet of paper obeys the laws of reflection, yet no image forms. What is the reason?

• A. The laws of reflection hold only for polished glass surfaces
• B. Light does not reflect from paper at all and only refracts into it
• C. The surface is irregular(correct answer)
• D. The paper absorbs the light before the laws of reflection can apply

Answer: C.The laws hold at every point, but the normals differ across a rough surface, so reflected rays scatter (standard knowledge, consistent with the chapter).

Q2. If a ray passes through a rectangular glass block, bending towards the normal on entering and away on leaving, how does the emergent ray compare to the incident ray?

• A. It is perpendicular to the incident ray
• B. It is along the surface of the block
• C. It is parallel to the incident ray but shifted sideways(correct answer)
• D. It is along the same line as the incident ray without any shift

Answer: C.The two bends are equal and opposite in a parallel-sided block, so the emergent ray is parallel to the incident ray but displaced (standard knowledge).

Q3. Arrange these in order of increasing speed of light: diamond, flint glass, water, air.

• A. Air, water, flint glass, diamond
• B. Diamond, flint glass, water, air(correct answer)
• C. Water, air, diamond, flint glass
• D. Flint glass, diamond, air, water

Answer: B.Higher n means lower speed, so the speeds increase as n falls from diamond (2.42) to flint glass (1.66), water (1.33) and air (1.00).

Q4. How is the normal related to the incident and reflected rays?

• A. It lies outside the plane that contains the two rays
• B. It is always parallel to the incident ray direction
• C. It lies between them and all three are in the same plane(correct answer)
• D. It coincides with the polished surface of the mirror

Answer: C.The first law says the incident ray, the reflected ray and the normal lie in the same plane, with the normal between the two rays.

Q5. A ray enters an equilateral glass prism and is incident on its first face along the normal. What happens at the first face and at the second face?

• A. No bending at the first face; it bends away from the normal at the second face(correct answer)
• B. It bends away from the normal at the first face and reflects at the second
• C. It bends towards the normal at the first face and again at the second face
• D. No bending at either face

Answer: A.At normal incidence there is no deviation at the first face, but the ray meets the second face obliquely and refracts away from the normal (standard knowledge).

Q6. In glass, which colour travels the slowest?

• A. Violet(correct answer)
• B. Red
• C. Yellow
• D. Green

Answer: A.The refractive index is highest for violet, so its speed in glass is lowest (standard knowledge from the dispersion explanation).

Q7. State the first law of reflection.

• A. The incident ray always travels along the normal and the reflected ray lies along the mirror surface
• B. The incident ray and the reflected ray are always at right angles to the mirror surface at that point
• C. The reflected ray is always bent towards the normal for the light that is falling on a smooth surface
• D. The incident ray, the reflected ray and the normal at the point of incidence all lie in the same plane(correct answer)

Answer: D.The first law of reflection says that the incident ray, the reflected ray and the normal at the point of incidence are coplanar.

Q8. Do the laws of reflection apply to curved mirrors?

• A. No, they hold only for plane mirrors and fail for any curved surface
• B. Yes, at each point the angle of incidence equals the angle of reflection, measured from the local normal(correct answer)
• C. Yes, but only the first law holds, not the second law
• D. No, because a curved mirror produces refraction instead of reflection

Answer: B.The laws hold at every point of any reflecting surface, with the normal taken perpendicular to the surface at that point (standard knowledge).

Q9. Why must a ray be reflected on the opposite side of the normal from the incident ray?

• A. The reflected ray goes back into the same medium and away from the incident side of the normal(correct answer)
• B. The reflected ray enters the mirror and travels to the other side of the normal
• C. The mirror pulls the ray across the normal by refraction
• D. The ray lies along the normal and so cannot stay on its original side

Answer: A.In reflection the ray returns to the first medium; the incident ray and the reflected ray lie on opposite sides of the normal.

Q10. In a simple demonstration with an upright plane mirror, which condition is placed on the object's height so that the whole object is seen?

• A. The object should be taller than the mirror
• B. The object should be exactly twice the height of the mirror
• C. The object should not be taller than the mirror(correct answer)
• D. The object should be placed behind the mirror

Answer: C.In the demonstration the object is kept no taller than the mirror, so its whole image can be seen (a mirror half the object's height would also be enough).