Question

A ray of light parallel to the principal axis of a spherical mirror falls at a point M as shown in the figure.

1. Identify the type of the mirror used in the diagram.

2. If focal length of the mirror is 10 cm, what is the distance CF in the figure?

3. Complete the ray diagram and mark the angle of incidence and angle of reflection.

4. If the mirror is immersed in water its focal length will be

• less than 10 cm
• 10 cm
• greater than 10 cm
• 20 cm

Answer 1

1. Concave mirror.

2. 10 cm (CF = PC – PF = R = f – 2f – f = f = 10 cm).

3. 

4. 10 cm. Focal length of mirror is independent of medium.