For finding the focal length of a concave mirror, where do we keep the object? What is the position of image formed? On which structure we get the image? What is the nature of the image formed?

Explanation

To find the focal length of a concave mirror, we need to follow a systematic approach. Here is the step-by-step solution:

### Step 1: Positioning the Object
- **Where do we keep the object?**
- We place the object at infinity. This means that the object is very far away from the mirror, allowing us to simplify the analysis of light rays.

### Step 2: Understanding the Image Position
- **What is the position of the image formed?**
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