An object is 2m from a lens which forms an erect image one-fourth (exactly) the size of the object. Determine the focal length of the lens. What types of lens is this?

Explanation

To solve the problem, we need to determine the focal length of the lens given the object distance and the magnification of the image formed. Here’s a step-by-step breakdown of the solution:

### Step 1: Understand the given information
- Object distance (U) = -2 m (negative because it is on the same side as the incoming light)
- The image formed is erect and one-fourth the size of the object.

### Step 2: Determine the magnification (M)
The magnification (M) is given by the formula:
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