Assertion (A) : A student is given a spherical mirror of focal length -10 cm. He identifies it as a concave mirror.

Reason (R) : Focal length of a concave mirror is always positive.

1. both A and R are true and R is the correct explanation of A
2. both A and R are true and R is not the correct explanation of A
3. assertion is false but reason is true
4. assertion is true but reason is false

What is a spherical mirror?

Define radius of curvature of a spherical mirror.

What is the aperture of a spherical mirror ?