State the relation between object distance, image distance and the focal length of a spherical mirror.

Question

(a) State the relation between object distance, image distance and the focal length of a spherical mirror.

(b) Draw a ray diagram to show the image formed by a concave mirror when an object is placed between the pole and focus of the mirror.

(c) A concave minor of focal length 15 cm forms an image of an object kept at a distance of 10 cm from the mirror. Find the position, nature and size of the image formed by it.

Answer 1

(a) The relation is 1/f = 1/v + 1/u

(b) The ray diagram is as shown below:

(c) Given, f = -15 cm, u = -10 cm, v = ?

Using the relation \(\frac{1}{f} = \frac{1}{u} + \frac{1}{v}\), we have

or v = 30 cm. Thus, the image is formed 30 cm behind the mirror. It is virtual and erect.