Define magnifying power of a telescope. Write its expression.
A small telescope has an objective lens of focal length 150 cm and an eye piece of focal length 5 cm. If this telescope is used to view a 100 m high tower 3 km away, find the height of the final image when it is formed 25 cm away from the eye piece.

Explanation

### Step-by-Step Solution

1. **Definition of Magnifying Power of a Telescope**:
The magnifying power (M) of a telescope is defined as the ratio of the angle subtended at the eye by the image to the angle subtended at the unaided eye by the object. It can also be expressed as:
\[ M = \frac{f_o}{f_e} \]
where \( f_o \) is the focal length of the objective lens and \( f_e \) is the focal length of the eyepiece lens.
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