A short object of length `L` is placed along the principal axis of a concave mirror away from focus. The object distance is `u`. If the mirror has a focal length `f`, what will be the length of the image ? You may take `L lt lt | u - f |`.

Explanation

To solve the problem of finding the length of the image formed by a concave mirror when a short object of length \( L \) is placed at a distance \( u \) from the mirror, we can follow these steps:

### Step 1: Understand the setup
We have a concave mirror with a focal length \( f \). A short object of length \( L \) is placed along the principal axis at a distance \( u \) from the mirror. The object is considered to be much smaller than the distance from the object to the focus, i.e., \( L \ll |u - f| \).

### Step 2: Define the positions of the object
Let’s denote the two ends of the object:
- The position of the left end of the object is \( u_1 = u - \frac{L}{2} \)
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