An astronomical telescope has a magnifying power of `10`. In normal adjustment, distance between the objective and eye piece is `22 cm` calculate focal length of objective lens.

Explanation

To solve the problem step by step, we will use the information given about the astronomical telescope and its magnifying power.

### Step 1: Understand the relationship between magnifying power and focal lengths
The magnifying power (M) of an astronomical telescope in normal adjustment is given by the formula:
\[ M = -\frac{F_O}{F_E} \]
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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