1. The focal length of a spherical mirror is related to its radius of curvature by the relation
(a) \(f = R\)
(b) \(f = 2R\)
(c) \(f = R/2\)
(d) \(f = 2/R\)
2. An object is placed at the centre of curvature of a concave mirror. The nature and position of the image formed are
(a) virtual, erect and behind the mirror
(b) real, inverted and at the centre of curvature
(c) real, inverted and between F and C
(d) virtual, erect and diminished
3. Which of the following is true for a ray of light passing through the optical centre of a thin lens?
(a) It bends towards the principal axis
(b) It emerges without any deviation
(c) It passes through the principal focus
(d) It is reflected back along the same path
4. Assertion (A): A convex mirror is preferred as a rear-view mirror in vehicles.
Reason (R): A convex mirror always forms a virtual, erect and diminished image and provides a wider field of view.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
5. When light travels obliquely from a rarer medium (air) to a denser medium (glass), it
(a) bends away from the normal
(b) bends towards the normal
(c) travels without deviation
(d) gets reflected totally
6. The absolute refractive index of a medium is the ratio of
(a) speed of light in the medium to speed of light in vacuum
(b) speed of light in vacuum to speed of light in the medium
(c) sine of angle of incidence to sine of angle of refraction
(d) focal length to radius of curvature
7. Assertion (A): The image formed by a plane mirror is always virtual, erect and laterally inverted.
Reason (R): In a plane mirror, the image distance equals the object distance and the image lies behind the mirror.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
8. For a concave mirror, the image is virtual and erect when the object is placed
(a) beyond C
(b) at C
(c) between F and C
(d) between P and F
9. The power of a lens of focal length –20 cm is
(a) +5 D
(b) –5 D
(c) +0.2 D
(d) –0.2 D
10. In the New Cartesian Sign Convention for spherical mirrors, distances measured to the right of the pole along the principal axis are taken as
(a) negative
(b) positive
(c) zero
(d) equal to focal length
11. Define the term ‘aperture’ of a spherical mirror. How does a small aperture affect the image formation?
12. State Snell’s law of refraction. Write the mathematical expression for it.
13. An object is placed at infinity in front of a convex mirror. Where is the image formed and what is its nature?
14. Differentiate between a real image and a virtual image formed by a spherical mirror (any two points).
15. What is meant by the statement “the refractive index of diamond is 2.42”?
16. A concave lens has focal length 15 cm. What is its power? Is the lens converging or diverging?
17. Draw a labelled ray diagram to show the formation of image by a concave mirror when the object is placed between its pole and principal focus. State two characteristics of the image formed.
18. With the help of a ray diagram, show how a convex lens converges a parallel beam of light rays. Mark the principal focus on the diagram.
19. An object 4 cm in size is placed at 25 cm in front of a concave mirror of focal length 15 cm. Using the mirror formula, find the position and nature of the image formed.
20. Explain why a pencil partly immersed in water appears to be bent at the water surface. Name the phenomenon responsible and state the two laws governing it.
21. List three uses of concave mirrors and give reasons why each use is suitable for a concave mirror.
22. (a) Draw a neat labelled diagram of the experimental set-up used to determine the focal length of a concave mirror.
(b) Describe the procedure and explain how the focal length is obtained from the observations.
(c) Why is it advised not to look directly at the Sun while performing this activity?
23. (a) State the mirror formula and magnification formula for a spherical mirror.
(b) An object 5 cm tall is placed at a distance of 20 cm in front of a convex mirror of focal length 30 cm. Using the mirror formula, calculate:
(i) the position of the image,
(ii) the magnification, and
(iii) the height and nature of the image.
Show all steps clearly.
24. (a) Draw ray diagrams to show image formation by a convex lens when the object is placed (i) at 2F₁ and (ii) between F₁ and the optical centre.
(b) For each case, state the position, nature and relative size of the image.
(c) How does the image change if the same object is viewed through a concave lens of same focal length?
25. Case: A student is standing at the terrace of Agra Fort and observes the full image of the Taj Mahal in a small mirror fitted on the wall. The mirror is curved outwards.
(a) Identify the type of mirror used and state one reason why it is preferred over a plane mirror.
(b) If the object (Taj Mahal) is considered at a very large distance, where would the image be formed?
(c) State two characteristics of the image formed by this mirror.
(d) What would happen to the field of view if a concave mirror were used instead?
26. Case: While performing an activity, a student places a glass slab over a straight line drawn on paper. When viewed from the side, the line appears bent at the edges of the slab.
(a) Name the phenomenon responsible for the apparent bending of the line.
(b) In which direction does the ray bend when it enters the glass slab from air?
(c) Why does the emergent ray become parallel to the incident ray?
(d) If the glass slab is replaced by a slab of diamond, would the lateral shift increase or decrease? Give reason.
27. Predict-and-justify: What would happen to the image formed by a concave mirror if the object is moved from a position between F and C to a position exactly at F? Justify your answer with ray diagram reasoning.
28. Analyse anomalous observation: In an experiment with a concave mirror, a student observes a sharp image on the screen when the object is beyond C, but when the object is moved slightly closer to F, the image disappears from the screen although the mirror is still reflecting light. Explain the reason for this observation.
29. Real-life application: A dentist needs to examine a small cavity in a patient’s tooth clearly. Which type of mirror should be used and why? Describe how the position of the tooth relative to the mirror affects the image characteristics.
30. Compare situations: Two identical objects are placed at the same distance in front of a concave mirror and a convex mirror of equal focal length. Compare the position, nature and size of the images formed in the two cases and justify the difference.
1. (c) — Recall of relation \(R = 2f\) (1 mark)
2. (b) — Table 9.1 recall (1 mark)
3. (b) — Ray through optical centre (1 mark)
4. (a) — Both true; wider field and erect image explain use (1 mark)
5. (b) — Refraction towards normal in denser medium (1 mark)
6. (b) — Definition of absolute refractive index (1 mark)
7. (a) — Both true; equal distances explain virtual/erect/lateral inversion (1 mark)
8. (d) — Table 9.1 (1 mark)
9. (b) — \(P = 1/f\) (in m) (1 mark)
10. (b) — New Cartesian Sign Convention (1 mark)
11. Diameter of reflecting surface (1 mark); small aperture ensures paraxial rays and sharp image (1 mark)
12. \(\frac{\sin i}{\sin r} =\) constant (1 mark); for given colour and pair of media (1 mark)
13. At principal focus F behind mirror (1 mark); virtual, erect, highly diminished (1 mark)
14. Real: can be obtained on screen, inverted (1 mark); Virtual: cannot be obtained on screen, erect (1 mark)
15. Speed of light in vacuum is 2.42 times speed in diamond (2 marks)
16. –6.67 D (1 mark); diverging (1 mark)
17. Correct ray diagram with two rays (2 marks); virtual, erect, enlarged, behind mirror (1 mark)
18. Parallel rays converge to principal focus after refraction (2 marks); labelled F (1 mark)
19. \(v = -37.5\) cm (2 marks); real, inverted (1 mark)
20. Refraction (1 mark); laws of refraction (1 mark); apparent shift due to change in speed (1 mark)
21. Any three uses with reasons (1 mark each)
22. Labelled diagram: mirror, paper screen, Sun rays converging at F (2 marks); procedure of moving screen till sharp spot, measure PF (2 marks); danger to eyes (1 mark)
23. (a) Formulae stated correctly (1 mark); (b)(i) \(v = +60\) cm (1.5 marks), (ii) \(m = +3\) (1 mark), (iii) virtual, erect, 15 cm (1.5 marks)
24. Two correct ray diagrams (2 marks); position/nature/size for each case (2 marks); diminished, virtual, erect for concave (1 mark)
25. (a) Convex mirror, wider field + erect image (1 mark); (b) at F behind mirror (1 mark); (c) virtual, erect, diminished (1 mark); (d) narrower field, inverted image possible (1 mark)
26. (a) Refraction (1 mark); (b) towards normal (1 mark); (c) equal and opposite bending at parallel faces (1 mark); (d) increase, higher refractive index (1 mark)
27. Image moves to infinity (1 mark); rays after reflection become parallel to principal axis (1 mark); no intersection on screen (1 mark)
28. Object reaches focal plane; image at infinity, cannot be caught on screen (2 marks); light still reflected but rays parallel (1 mark)
29. Concave mirror (1 mark); tooth between P and F gives enlarged virtual image (2 marks)
30. Concave: real/inverted (depending on position) (1 mark); Convex: always virtual, erect, diminished (1 mark); difference due to converging vs diverging nature (1 mark)
All questions are answerable from the NCERT chapter text. Reviewed by GFIS faculty.