Osb India Optics DPP Class 10

                                                   Osb India Optics DPP Class 10 

1. In reflection of light the angle of reflection is
a) equal to angle of incidence b) greater than angle of incidence c) less than angle of incident d) Both (a) &(b)
2. When light travel from  air to glass it
a) bend away from normal b) bend towards the normal c)does not bend d)none of these
3. Refraction causes due  to a) change in wavelength of light b) change in speed of light c) change in frequency of light d) Both (a) & (c)
4. The correct relationship between refractive index and speed of light is a) u=c/v b) u = v/c c) u=v×c d) u=v+c
5. The speed of light in water is 2.25 ×10^8 m/s then refractive index of water is a) 2.32 b)1.03 c)1.33  d)2.33
6. The refractive indices of kerosene oil, water and turpentine oil are 1.44, 1.33, 1.47 respectively. In which of these material light travel faster? a) Kerosene oil b) Turpentine oil c) water d) Equal in all
7. A coin dipped in water seem raised  because of a) scattering of light b) internal reflection c) Refraction of light d) diffraction of light
8. The diamond has maximum refractive index then it’s critical angle will be a) lowest b)highest c) zero d) equal
9. In total internal reflection a) angle of incidence is less than the critical angle b) angle of incidence is not equal to critical angle c) angle of incidence is equal to critical angle d) angle of incidence is greater than the critical angle
10. Mirage in desert and on road .which of following physical phenomenon are responsible for this.
a) Internal reflection b) Refraction c) Reflection d) deviation
11. which ray is less deviated by prism a) yellow ray b)red ray c) Violet ray d) Green ray
12.

Assertion (A) In case of refraction of light through glass slab, angle of incidence is equal to angle of emergence. Reason (R) A glass slab is cuboid made of glass in which refraction occurs twice from the corresponding parallel surfaces. (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) R is true, but A is false
13. Absolute refractive index of some materials A, B, C and D are given as below:
Medium A B C D Refractive index 1.54 1.33 2.42 1.65 Respectively, In Which medium speed of light is fastest
(a) A (b) B (c) C (d) D
14. Two lenses of power − 3.5 D and + 1.0 D one placed in contact with each other. What is the focal length of this combination? (a) 10 cm (b) 20 cm (c) 30 cm (d) 40 cm
15. When the object is at infinity, what is the nature of image formed by concave lens? (a) Real, inverted, enlarged (b) Real, inverted, same size (c) Virtual, erect, enlarged (d) Virtual, erect, diminished
16. A convex lens of focal length 40 cm, a concave lens of focal length 40 cm and a concave lens of
focal length 15 cm are placed in contact. The power of the combination in dioptre is
(a) +1.5 (b) −1.5 (c) + 6.67 (d) − 6.67
17. A needle placed 45 cm from a lens forms an image on a screen placed 90 cm on the other side of the lens. What is the power of the lens? (a) +10 D (b) −10 D (c) +3.33 D (d) −3.33 D
18. An incident ray strike a plane mirror at an angle of 150 with the mirror. The angle between the
incident ray and reflected ray is (A) 15⁰ (B) 30⁰ (C) 150⁰ (D) none of these
19. In case of a virtual and erect image, the magnification of a mirror is
(A) positive (B) negative (C) unity (D) infinity

20. A virtual, erect and magnified image of an object is to be produced with a concave mirror of focal length 12 cm. Which of the following object distance should be chosen for this purpose?

(A) 10 cm (B) 14 cm (C) 18 cm (D) 24 cm
21. The mirror used in automobiles to see the rear field of view is (A) concave (B) convex (C) plane (D) none of these
22. Which is the wrong statement out of the following (A) A concave mirror can give a virtual image. (B) A convex mirror can give a virtual image. (C) A concave mirror can give a diminished virtual image. (D) A convex mirror cannot give a real image.
23. When an object is placed between the focus and the pole of a concave mirror, the image formed i
(A) real, inverted and small (B) real, inverted and same size (C) real, inverted and enlarged (D) virtual, erect and enlarged
24. The mirror used by dentists to concentrate light on the tooth to be examined is..........mirror
(A) concave (b) convex (B) plane or concave (D) plane
25. An object is placed in front of a convex mirror at a distance of 50 cm. A plane mirror is introduced covering the lower half of the convex mirror. If the distance between the object and the plane mirror is 30 cm, it is found that there is no parallax between the image formed by the two mirrors. What is the radius of curvature of the convex mirror? (A) 25 cm (B) 7 cm (C) 18 cm (D) 27 cm
26. The distance between a real object and its image in a convex mirror of focal length 12 cm is 32 cm find the size of image if the object size is 1 cm. (A) 2/3 cm (B) 1/3 cm (C) 1 cm (D) 1⁄4 cm
27. An object 15 cm high is placed 10 cm from the optical centre of a thin lens. Its image is formed 25 cm from the optical centre on the same side of the lens as the object. The height of the image is
(A) 2.5 cm (B) 0.2 cm (C) 16.7 cm (D) 37.5 cm
28. A convex lens forms an images of an object placed 20 cm away from it at a distance of 20 cm on the other side of the lens. If the object is moved 5 cm toward the lens, the image will be
(A) 5 cm towards the lens (B) 5 cm away from the lens (C) 10 cm towards the lens (D) 10 cm away from the lens
29. Which of the following can make a parallel beam of light when light from a point source is incident on it? (a) Concave mirror as well as convex lens (b) Convex mirror as well as concave lens (c) Two plane mirrors placed at 90° to each other (d) Concave mirror as well as concave lens
30. A 10 mm long awl pin is placed vertically in front of a concave mirror. A 5 mm long image of the awl pin is formed at 30 cm in front of the mirror. The focal length of this mirror is
(a) – 30 cm (b) – 20 cm (c) – 40 cm (d) – 60 cm
31. Under which of the following conditions a concave mirror can form an image larger than the actual object? (a) When the object is kept at a distance equal to its radius of curvature (b) When object is kept at a distance less than its focal length (c) When object is placed between the focus and centre of curvature (d) When object is kept at a distance greater than its radius of curvature
32. Which of the following statements is true? (a) A convex lens has 4 dioptre power having a focal length 0.25 m (b) A convex lens has –4 dioptre power having a focal length 0.25 m (c) A concave lens has 4 dioptre power having a focal length 0.25 m (d) A concave lens has –4 dioptre power having a focal length 0.25 m
33. Magnification produced by a rear view mirror fitted in vehicles (a) is less than one (b) is more than one (c) is equal to one (d) can be more than or less than one depending upon the position of the object in front of it