Why are mirrors used in search lights parabolic and not concave sphrical ?

Explanation

### Step-by-Step Solution:

1. **Understanding Mirror Types**:
- There are different types of mirrors used in optical devices, primarily concave spherical mirrors and parabolic mirrors.

2. **Behavior of Light Rays**:
- When light rays emanate from a point source placed at the focus of a concave spherical mirror, they reflect off the mirror and ideally should be parallel to the principal axis. However, this is only true for rays that are close to the principal axis (paraxial rays).

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