A 6 m tall tree is at a distance of 18 m from a pin hole camera. Where should a screen be placed to obtain a 20 cm tall image of the tree ?

Explanation

To solve the problem, we need to find the position of the screen in a pinhole camera setup that will produce a specific image size of a tree. Here’s a step-by-step solution:

### Step 1: Identify the given values
- Height of the tree (object), \( h_o = 6 \, \text{m} \)
- Distance of the tree from the pinhole camera (object distance), \( u = -18 \, \text{m} \) (negative because it is on the opposite side of the light direction)
- Height of the image, \( h_i = -20 \, \text{cm} = -0.2 \, \text{m} \) (negative because the image is inverted)

### Step 2: Use the magnification formula
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