Which of the following can make a parallel beam of light when light from a point source is incident on it?
- Concave mirror as well as convex lens
- Convex mirror as well as concave lens
- Two plane mirrors placed at 90° to each other
- Concave mirror as well as concave lens
When a point light source is placed at the focus of concave mirror then it all light rays after reflection through mirror will become parallel to the principal axis. When this point light source is placed at the focus of convex lens then after falling on convex lens it will become parallel to the principal axis.
The correct option is A.