A concave mirror has a focal length of 15 cm. A 10 cm long iron scale is placed coaxially to the principal axis such that end away from the mirror is 40 cm away from the pole. What will be length of the image ?

Explanation

To solve the problem, we need to find the length of the image formed by a concave mirror when a 10 cm long iron scale is placed coaxially with the principal axis. The end of the scale that is away from the mirror is 40 cm from the pole of the mirror.

### Step-by-Step Solution:

1. **Identify the given values:**
- Focal length of the concave mirror, \( f = -15 \, \text{cm} \) (negative because it's a concave mirror).
- Length of the scale, \( L = 10 \, \text{cm} \).
- Distance of the far end of the scale from the mirror, \( d_B = 40 \, \text{cm} \).
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