Self inductance of an air core inductor increases from 0.01 mH to 10 mH when an iron core is introduced in it. What is the relative permeability of the core ?

Explanation

To find the relative permeability of the iron core, we can follow these steps:

### Step 1: Understand the relationship between inductance and permeability
The self-inductance \( L \) of a solenoid is given by the formula:
\[ L = \frac{\mu n^2 A}{l} \]
where:
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