An object is placed at a distance of 40 cm from a concave mirror of focal length 15 cm. If the object is displaced through a distance of 20 cm towards the mirror, the displacement of the image will be

Step-by-step solution

By mirror formula, v 1 = u f u - f = - 40 - 15 - 40 + 15 = 600 - 25 = - 24   c m   When object is displaced by 20 cm towards mirror v 2 = u f u - f = - 20   - 15 - 20 + 15 = - 60   c m Displacement of image = v 2 - v 1 = - 36   c m = 36 cm away from the mirror