Ray Optics and Optical Instruments Mock Test – Class 12 Physics

1. A monochromatic ray passes from medium of refractive index into medium of refractive index . The ratio of its wavelength in medium to that in medium is

2. A student measures the angle between an incident ray and a plane mirror surface as . The reflected ray will make what angle with the normal?

3. A simple microscope forms its final image at the near point. If and , the magnifying power is

4. An optical device is useful in ray optics when its action can be understood by following the change in direction of light rays. A suitable example is

5. A thin prism has , , and dispersive power . The angular dispersion between violet and red is

6. Assertion: A reflecting telescope can be made with a very large objective more conveniently than a refracting telescope.
Reason: A mirror objective can be supported from behind, while a large lens objective must transmit light through its full aperture.

7. A compound microscope has , , and . Taking , the percentage increase in magnifying power when adjusted from final image at infinity to final image at near point is

8. A thin-lens combination has equivalent focal length , and a real object is placed in front of it. The image distance and magnification are

9. A glass lens is placed in a liquid having the same refractive index as the glass. The lens becomes ineffective for focusing because

10. A concave mirror produces an inverted image that is larger than the object. The most suitable object position is

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

12. Chromatic aberration is absent in a reflecting telescope objective because

13. A ray goes from diamond to air. Diamond has a high refractive index, so its critical angle is small. This helps explain why a well-cut diamond appears brilliant because

14. A thin-prism relation is used for two colours in the same prism. If , then

15. A convex lens gives a real image at when a real object is at . The focal length is

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

17. 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.

18. In regular reflection at a plane mirror, the incident ray, reflected ray, and normal at the point of incidence

19. A telescope has aperture and works with light of wavelength . Another telescope has aperture and works with light of wavelength . The ratio of their diffraction-limited angular separations is

20. In a compound microscope, increasing the tube length while keeping , , and fixed generally

21. A concave mirror of radius of curvature is used to form a real image of an object placed in front of it. The magnification is

22. A telescope in normal adjustment has and . Its angular magnifying power is

23. Assertion: At minimum deviation, the refractive-index formula for a prism can be written using only and .
Reason: At minimum deviation, and , so Snell's law can be expressed in terms of and .

24. A person sees an image in a plane mirror, but a screen placed behind the mirror does not catch that image. The best interpretation is that the image is

25. A concave mirror is used as a shaving mirror. The face must be placed

26. The dispersive power of a prism material is commonly expressed as

27. Consider the following statements about basic spherical-mirror geometry:
I. The centre of curvature lies on the principal axis.
II. The radius of curvature is the distance .
III. The principal focus of a concave mirror is virtual for paraxial parallel rays.
IV. The relation is used for spherical mirrors in the paraxial approximation.
The suitable set is

28. A coin at the bottom of a water vessel appears raised when viewed nearly normally from air. This happens because

29. A microscope objective has high magnification but poor resolving ability. The image of two very close points will most likely appear as

30. In a Galilean telescope in normal adjustment, the approximate length of the instrument is

31. Magnifying power of a visual instrument is best described as a comparison between

32. In a convex spherical mirror, paraxial rays parallel to the principal axis after reflection appear to diverge from a point behind the mirror. This point is the

33. A table compares atmospheric colour phenomena:

The suitable rows are

34. A structure-function record for the human eye is given below:

The suitable rows are

35. A telescope is mainly used to view

36. The spectacle lens used to correct myopia is

37. A graph is planned using the spherical refracting surface formula. If is plotted on the vertical axis and on the horizontal axis for fixed , , and , the graph should have

38. An object is placed in front of a plane mirror. The distance between the object and its image is

39. Two reflected rays from a concave mirror meet at a point below the principal axis after reflection. This point represents

40. During sunrise and sunset, the Sun often appears reddish because

41. In the situation , , and for a convex lens, the magnification is

42. When a light ray passes obliquely from air into glass, it bends toward the normal mainly because

43. A thin convex lens has power . A real object is placed in front of it. The image distance is

44. Two simple microscopes have focal lengths and . For final image at the near point, the ratio of their magnifying powers is

45. The angle of prism is the angle between

46. A single convex lens is used to see a small stamp clearly with final image at the near point. A two-lens instrument is used to see bacteria on a slide. A long objective with a short eyepiece is used to see the Moon. The three instruments are respectively

47. The formula and the formula are used for different instruments. The first applies to a

48. A graph is described for a convex lens where the object moves from far beyond toward , and the vertical axis shows real image size. Before the object reaches , the image size generally

49. In a separated-lens calculation, all distances are first written in . The safest way to use is to

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