Ray Optics and Optical Instruments Mock Test – Class 12 Physics

1. A spherical refracting surface separates two transparent media. Its radius of curvature is measured from

2. A graph is described with object position for a concave mirror moving from far beyond toward on the horizontal axis and image size on the vertical axis. Before the object reaches , the graph should show that the real image size generally

3. A compound microscope has , , , and . Its approximate magnifying power for final image at the near point is

4. A pair of thin lenses in contact has equivalent power . This means the combination behaves like

5. If the real depth of an object in a liquid is and its apparent depth is , the refractive index of the liquid relative to air is

6. A small-particle scattering experiment uses violet light of wavelength and red light of wavelength . The ratio is

7. A convex lens has focal length . An object is placed in front of it. The image distance is

8. In refraction at a spherical surface, the formula uses for the medium in which

9. Assertion: Total internal reflection is possible for a ray going from water to air, but not for a ray going from air to water.
Reason: Total internal reflection requires the incident ray to be in the optically denser medium.

10. The real and apparent depths for three liquids are recorded for near-normal viewing from air:

The liquid with the greatest refractive index is

11. In a plane mirror, the image of a real object is described as erect. This means that

12. A learner mixes up microscope and telescope formulas. The expression belongs to

13. For a convex lens placed in air, the principal focus on the right side of the lens is used when parallel rays from the left converge after refraction. With light travelling from left to right, the focal length of the convex lens is

14. The following records are made for thin lenses kept in contact:

The acceptable rows are

15. Two thin lenses of powers and are kept in contact. The equivalent power is

16. A prism of angle is adjusted to minimum deviation. If the minimum deviation is , the angle of incidence is

17. A glass slab appears thinner than its actual thickness when viewed normally from air. If the refractive index of glass is , the actual thickness is

18. In a desert mirage, the lower air layer near the hot ground has

19. A transparent slab of thickness and refractive index produces apparent shift . If is increased while is unchanged, the apparent shift

20. Rayleigh scattering is strongest for light of

21. The following comparisons are made for optical fibres:

The correct rows are

22. A graph is described for a convex mirror with object distance magnitude increasing along the horizontal axis and image distance behind the mirror along the vertical axis. As the object becomes very far away, the image position approaches

23. A real object is placed in front of a spherical refracting surface. Light travels from air into glass , and the surface has . The image distance and lateral magnification are

24. In mirror problems, the magnification relation is useful because it gives

25. An object is placed between and in front of a concave mirror. The image is expected to be

26. Accommodation of the eye means the ability of the eye lens to

27. Presbyopia commonly occurs with age because

28. A plane mirror is used to view an object of height . Neglecting thickness and distortion, the image height is

29. The main difference between magnification and resolution is that magnification describes

30. Assertion: Interchanging and in the spherical refracting surface formula generally changes the result.
Reason: and represent the incident and refracted media, so their placement carries the direction of light crossing the surface.

31. A ray diagram for a spherical refracting surface is drawn using only paraxial rays. This restriction is used because

32. A ray is incident normally on one face of a rectangular glass slab. The lateral displacement after emerging from the second face is

33. A spherical refracting surface is convex as seen by incident light from the left. Its centre of curvature lies to the right of the pole. Under the usual Cartesian sign convention, is

34. A compound microscope has objective focal length , eyepiece focal length , tube length , and near point . For final image at the near point, the approximate magnifying power is

35. The far point of a normal eye is

36. A student writes the microscope magnification as . The main correction is that the objective factor should be

37. Light travels from glass into air through a concave spherical surface whose centre of curvature is on the incident side. If and , the image distance is

38. A ray is directed through the principal focus of a concave mirror before striking the mirror. After reflection, the ray becomes

39. A student says, “Since a rainbow contains colours, it must be caused only by scattering like the blue sky.” The better correction is that a rainbow is mainly due to

40. A microscope and a telescope are both included in ray optics because their working can be started by studying

41. A result table for refraction at a spherical surface is shown:

The acceptable rows are

42. A ray parallel to the principal axis of a concave mirror is reflected so that it passes through

43. A biconvex lens has focal length in air. When immersed in a liquid, its focal length becomes . If the lens material has refractive index , the refractive index of the liquid is

44. A convex mirror of focal length forms an image of an object placed in front of it. If the object height is , the image height is

45. A spherical mirror has radius of curvature and focal length . The most suitable unit pair for these two quantities is

46. Consider the following statements about refraction:
I. The angles in Snell's law are measured from the normal.
II. At a boundary, the frequency of a light wave remains unchanged.
III. If , an obliquely incident ray bends toward the normal in medium .
The suitable choice is

47. The order of deviation of colours in a glass prism, from least to greatest, is

48. A telescope has normal-adjustment magnifying power . Its eyepiece focal length is changed from to , while the objective focal length is unchanged. The new magnifying power is

49. For a real object placed anywhere in front of a convex mirror, the image is formed

50. A ray inside a transparent medium of refractive index is incident on the medium-air boundary. If , the ray