Question

 A point object is placed on the principal axis of a concave mirror quite far away from the pole and moved at a constant speed 0.5 cm s -1 towards the pole. Its image also moves. It is found that the object and the image cross each other at a point 50 cm from the place.

Question(14)

Time taken by the image to move from centre of curvature to the infinity is
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Answer 1

Explanation:

The relationship between the radius of curvature and focal length is that the radius of curvature is twice the focal length. In other words, focal length is half the radius of curvature.

In this case, radius of curvature of the concave mirror is given as 40 cm. Hence, the focal length of the mirror is

2

40

=20cm.

Hence, the focal length of the