A concave mirror can be used to produce a parallel beam of light if a lighted bulb is placed
- between its focus and the pole
-
at its focus
- at its centre of curveture
- between its focus and centre of curvature
The correct answer is: B
Explanation
When a light source is placed at the focus of a concave mirror, the rays of light that reflect off the mirror will emerge as a parallel beam of light.
This happens because when a point source of light is placed at the focal point of a concave mirror, the reflected rays leave the mirror parallel to each other.