Question

Describe the positions of the source of light with respect to a concave mirror in 1. Torch light, 2. Projector lamp, 3. Floodlight. (From Reflection of light chapter)

Answer 1

Before answering this question, let me explain some basic things to you.
Concave Mirror:
A concave mirror is the mirror that is covered inward in the middle. The type of image the mirror will make depends on two things. The position where the object is located infront of the mirror and the focal length of the mirror.
Principle Focus:
The rays travelling through a concave mirror converge at point F after passing through a mirror. This point is known as the principle focus of the concave mirror.
Center Of Curvature:
The point in the center of the sphere from which the mirror was sliced is known as the center of curvature and is denoted by C.
Position of Source Light:
1. Torch Light:
The source of light is placed at the focus F.
2. Projector Lamp:
The source of light is placed at the center of curvature.
3. Floodlight:
The source of light is placed beyond the center of curvature.

Answer 2

1. In a torch light, the source of light is placed at the focus of the concave mirror to obtain a parallel beam of light.

2. In a projector lamp, the source of light is placed at the centre of curvature of the concave mirror.

3. In a floodlight, the source of light is placed just beyond the centre of curvature of the mirror.