#### Light - Important Question Paper

9th Standard

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Science

Time : 01:00:00 Hrs
Total Marks : 50

Part A

5 x 1 = 5
1. The field of view * is maximum for ________

(a)

plane mirror

(b)

concave mirror

(c)

convex mirror

2. When a ray of light passes from one medium to another medium, refraction takes place when angle of incidence is

(a)

0o

(b)

45o

(c)

90o

3. When the reflecting surface is curved outwards the mirror formed will be

(a)

concave mirror

(b)

convex mirror

(c)

plane mirror

4. The focal length of a concave mirror is 5cm. Its radius of curvature is

(a)

5 cm

(b)

10 cm

(c)

2.5 cm

5. The speed of light is maximum in

(a)

vacuum

(b)

glass

(c)

diamond

6. Part B

5 x 1 = 5
7. The mirror used in search light is ________ .

()

Concave

8. The angle of deviation of light ray in a prism depends on the angle of _________

()

incident

9. A spherical mirror whose reflecting surface is curved outwards is called ___________ mirror

()

10 cm

10. Large _________ mirrors are used to concentrate sunlight to produce heat in solar furnaces

()

concave reflector

11. All distances parallel to the principal axis are measured from the ____________ of the mirror

()

pole

12. Part C

6 x 2 = 12
13. The speed of light in air is 3 $\times$ 108ms-1 and in glass it is 2 $\times$ 108ms-1 what is the refractive index of glass

14. Give two examples of transparent medium that are denser than air

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

16. Name the mirror(s) that can give (i) an erect and enlarged image, (ii) same sized, inverted image

17. If an object is placed at the focus of a concave mirror, where is the image formed?

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

19. Part D

6 x 3 = 18
20. An object 2 cm high is placed at a distance of 16 cm from a concave mirror which produces a real image 3 cm high. Find the position of the image.

21. a) Complete the diagram to show how a concave mirror forms the image of the object.
b) What is the nature of the image?

22. Pick out the concave and convex mirrors from the following and tabulate them
Rear-view mirror, Dentist’s mirror, Torch-light mirror, Mirrors in shopping malls, Make-up mirror.

23. State the direction of incident ray which after reflection from a spherical mirror retraces its path. Give reason for your answer.

24. What is meant by magnification? Write its expression. What is its sign for the
a) real image b) virtual image

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

26. Part E

2 x 5 = 10
27. a) Draw ray diagrams to show how the image is formed, using a concave mirror when the position of object is i) at C ii) between C and F iii) between F and P of the mirror.
b) Mention in the diagram the position and nature of image in each case.

28. Explain with diagrams how refraction of incident light takes place from
a) rarer to denser medium
b) denser to rarer medium
c) normal to the surface separating the two media.