Light reflection and refraction Worksheet-32

Light reflection and refraction Worksheet-32

11. If an object is placed 10 cm in front of a concave mirror of focal length 20 cm the image will be

A. Diminished, upright, virtual

B. Enlarged, upright, virtual

C. Diminished, inverted, real

D. Enlarged, upright, real

12. Under which of the following conditions will a convex mirror of focal length f produce an image that is erect, diminished and virtual

A. Only when 2f > u > f               B. Only when u = f

C. Only when u < f                       D. Always

13. To an observer on the earth the stars appear to twinkle. This can be ascribed to

A. The fact that stars do not emit light continuously

B. Frequent absorption of star light by their own atmosphere

C. Frequent absorption of star light by the earth's atmosphere

D. The refractive index fluctuations in the earth's atmosphere

14. The ratio of the refractive index of red light to blue light in air is

A. Less than unity

B. Equal to unity

C. Greater than unity

D. Less as well as greater than unity depending upon the experimental arrangement

15. Light of different colours propagates through air

A. With the velocity of air

B. With different velocities

C. With the velocity of sound

D. Having the equal velocities

16. Which of the following is not a correct statement

A. The wavelength of red light is greater than the wavelength of green light

B. The wavelength of blue light is smaller than the wavelength of orange light

C. The frequency of green light is greater than the frequency of blue light

D. The frequency of violet light is greater than the frequency of blue light

17. The time taken by sunlight to cross a 5 mm thick glass plate (μ = 3/2) is

A. 0.25 × 10^–7 S                             B. 0.167 × 10^–7 S

C. 2.5 × 10^–10 S                              D. 1.0 × 10^–10 S

18. The distance travelled by light in glass (refractive index = 1.5)  in a nanosecond will be

A. 45 cm            B. 40 cm            C. 30 cm            D. 20 cm

19. When the bottom of a container which is filled with some liquid is viewed from top, appears slightly raised because of ____ of light.

A. Refraction                                 B. Interference

C. Diffraction                                D. Reflection

20. Electromagnetic radiation of frequency n, wavelength λ, traveling with velocity v in air, enter a glass slab of refractive index μ. The frequency, wavelength and velocity of light in the glass slab will be respectively.

A.                                      B.

C.                                        D.

Answer Key:

11. B
12. D
13. D
14. A
15. D
16. C
17. A
18. D
19. A
20. B