Light reflection and refraction Worksheet-13

Light reflection and refraction Worksheet-13

1. A ray of light passing through centre of curvature of a concave mirror retraces its path on reflection. Why?

2. A ray of light passing through focus of a concave mirror becomes parallel to the principal axis of the mirror on reflection. True or false

3. Does the position, size and nature of the image formed by a concave mirror depend on the position of the object ?

4. Where is the image formed when an object is at large distance from a concave mirror ?

5. A concave mirror serves as doctor's head mirror. How ?

6. Where should an object be placed in front of a concave mirror to obtain an image, which is real, inverted and reduced in size ?

7. For what position of an object, a concave mirror forms a real image equal in size to the object ?

8. Is the position of image same as the position of object when object and image sizes are equal ?

9. Can a concave mirror form a virtual image of same size as the object ?

10. The formula for linear magnification is same for convex and concave mirrors. True or false ?

11. Which mirror has a larger field of view: convex or concave ?

12. To see enlarged image of an object, will you use a convex mirror or a concave mirror ?

13. Where should an object be placed so that a real and inverted image of the same size is obtained using a convex lens ?

14. An object 2 cm high Is placed at a distance 2 f from a convex lens. What is the height of the image formed ?

15. What is the largest value of refractive index ? Name the medium.

16. What are the units of refractive index ?

17. Arrange air, glass and water in terms of decreasing refractive index.

18. A convex lens has a real focus and a concave lens has a virtual focus. Is it true ?

19. If the image formed by a convex lens is of the same size as that of the object, what is the distance of object from the lens ?

20. The image formed by a convex lens is always real. Is it true ?

Answer:

1. This is because such a ray falls normally on the mirror ∠I = 0°, ∠r = ∠i = 0°.

2. Yes, it is true.

3. Yes

4. The image formed is at the focus of the mirror.

5. This is because a concave mirror can form, virtual, erect and magnified image of the object.

6. The object must be placed beyond the centre of curvature.

7. The object must be at the centre of curvature of the mirror.

8. Yes, object and image positions are the same that is at the centre of curvature.

9. No, virtual image formed by a concave mirror is always enlarged.

10. True

11. Convex mirror has larger field of view.

12. A concave mirror.

13. The object should be placed at a distance equal to twice the focal length of the lens.

14. The height of image = the height of the object = 2 cm.

15. 2.42 for diamond.

16. It is a medium so it has no units.

17. Glass : ^an_g = 1.5

Water: ^an_w = 1.33

Air : n_a = 1.0003

18. Yes

19. The distance of the object from the convex lens is equal to twice the focal length of the lens.

20. No. A convex lens may also form a virtual image.