We use a concave polished metallic surface as a reflector in a torch to obtain a parallel beam of light. The position of the bulb is :

1. at the centre of curvature of the reflector.
2. at the focus of the reflector
3. between the focus and centre of curvature of the reflector
4. can be any of the above options

What is a spherical mirror?

Define radius of curvature of a spherical mirror.

What is the aperture of a spherical mirror ?