#### Light Model Question Paper

9th Standard

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Science

Time : 01:00:00 Hrs
Total Marks : 40
5 x 1 = 5
1. A real and enlarged image can be obtained by using a

(a)

convex mirror

(b)

plane mirror

(c)

concave mirror

2. Which of the following statements about total internal reflection is true?

(a)

angle of incidence should be greater than critical angle

(b)

light must travel from a medium of higher refractive index to a medium of lower refractive index

(c)

both (a) and (b)

3. The angle between the normal and the refracted ray is called angle of ________________________

(a)

reflection

(b)

refraction

(c)

incidence

(d)

deviation

4. The second law of refraction is stated by ____________________

(a)

C.V. Raman

(b)

Gallileo

(c)

Newton

(d)

Snell

5. The velocity of light in air is______________

(a)

$1.8\times { 10 }^{ 8 }$m/s

(b)

$3\times { 10 }^{ 8 }$m/s

(c)

$2.25\times { 10 }^{ 8 }$m/s

(d)

$3\times { 10 }^{ 6 }$m/s

6. 5 x 2 = 10
7. According to cartesion sign convention, which mirror and which lens has negative focal length?

8. A coin in a glass beaker appears to rise as the beaker is slowly filled with water, why?

9. Copy this figure in your answer book and show the direction of the light ray after reflection

10. What happens when a ray of light travels from rarer medium to the denser medium?

11. What happend when a ray of light travels from denser medium to rarer medium?

12. 5 x 3 = 15
13. What is meant by magnification? Write its expression. What is its sign for the
a) real image b) virtual image

14. Write the spherical mirror formula and explain the meaning of each symbol used in it.

15. Why do stars twinkle?

16. What is the reason for the brilliance of diamond?

17. Write the uses of convex and concave mirros.

18. 2 x 5 = 10
19. State and verify laws of refraction using a glass slab

20. The radius of curvature of a convex mirror is 30 cm. Find its focal length.