Velocity of Image in a Concave Mirror – Rankers Physics
Topic: Ray Optics
Subtopic: Reflection by Spherical Mirrors

Velocity of Image in a Concave Mirror

A point object is moving towards a concave mirror of focal length \(25\text{ cm}\). When it is at a distance of \(20\text{ cm}\) from the mirror, its velocity is \(5\text{ cm/sec}\). Find velocity of image at that instant :-
10 cm/sec
125 cm/sec
25 cm/sec
5 cm/sec

Solution:

Using the relation between object and image velocity: \(v_i = -m^2 v_o\). Here, magnification \(m = \frac{f}{f-u} =\frac{-25}{-25 - (-20)} = 5\). Hence, \(v_i = -5^2 \times 5 = -125\text{ cm/s}\). The speed is \(125\text{ cm/s}\).

Leave a Reply

Your email address will not be published. Required fields are marked *