When a resistance of 11 `Omega` is connected in series with an electric cell, 0.5 A current flows thrugh it . If the 11 `Omega` resistor is replaced by `5 Omega` resistor the current flowing through it is 0.9 A . Find the internal resistance of the cell.

Explanation

To find the internal resistance of the cell, we can follow these steps:

### Step 1: Write down the formula for current in a circuit
The current \( I \) flowing through a circuit with an electromotive force (emf) \( E \), an external resistance \( R \), and an internal resistance \( r \) can be expressed as:
\[ I = \frac{E}{R + r} \]

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