An astronomical telescope has an objective of focal length 20 cm and an eyepiece of focal length 4.0 cm. The telescope is focused to see an object 10 Km from the objective .The final image is formed at infinity. Find the length of the tube and the angular magnification produced by the telescope.

Explanation

To solve the problem step by step, we will find the length of the tube and the angular magnification produced by the telescope.

### Step 1: Identify the given values
- Focal length of the objective lens (F₀) = 20 cm
- Focal length of the eyepiece (Fₑ) = 4 cm
- Object distance (u) = 10 km = 10,000 m = 10,00,000 cm (since we need to convert to cm for consistency)

### Step 2: Determine the image distance from the objective lens
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