Question

5. A ray is reflected in turn by two plane mirrors,inclined at right angle with each other. Find the angle between incident and reflected ray.
6. A concave mirror is made by cutting a hollow thin glass sphere of radius 30 cm. Find its focal length.
7. What will be nature of image formed by a concave mirror, if the object is between focus and centre of curvature?
8. Two thin lenses of powers 4 D and -2 D are placed in contact. What is the focal length of the
combination?
9.Three thin convex lenses of focal length fi, f, and f are placed in contact coaxially. What will be
effective power of combination?
10. A candle is held 3 cm away from a concave mirror of radius of curvature 24 cm. What will be the
distance of image from mirror?
11. Calculate the speed of light in (i) glass (ii) water.
Refractive index of glass is 1.5 and water is 1.33.
(Take speed of light in air or vacuum, c = 3 x
108 m/s)
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Answer 1

Explanation:

6.the radius of curvature is 30 so the focal length is -15.

7.the nature of image is real and inverted.