What is meant by magnification?
Write its expression for spherical mirror.
What is its sign for the
(a) real image
(b) virtual image?

Explanation

### Step-by-Step Solution:

1. **Definition of Magnification**:
- Magnification refers to the increase in size of an image compared to the size of the object. It indicates how much larger or smaller the image appears relative to the actual object.

2. **Mathematical Expression for Magnification**:
- The magnification (m) can be expressed in two ways:
- **Height-based expression**:
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