A circular coil of 60 turns and radius 4 cm carries current of 1 A . How much work will be done in rotating the coil through `90^(@)` . It is suspended freely in uniform magnetic field `0.2 T`.

Explanation

To solve the problem of how much work is done in rotating a circular coil through 90 degrees in a uniform magnetic field, we will follow these steps:

### Step 1: Calculate the Area of the Coil
The area \( A \) of a circular coil is given by the formula:
\[ A = \pi r^2 \]
where \( r \) is the radius of the coil. Given that the radius is 4 cm, we first convert it to meters:
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