A coil made of 10 turns of a wire wound in a circular loop of radius` 0.02` m, carries a current of `0.5 ^^` and is placed inside a solenoid of 400 tums and length `0.5` m. If the solenoid carries a current of `0.2` A, what torque will be required to hold the coil in the centre of the solenoid when placed with its plane along the axis of solenoid.

Explanation

To solve the problem, we need to calculate the torque required to hold a coil in the center of a solenoid. The coil has 10 turns and carries a current of 0.5 A, while the solenoid has 400 turns and carries a current of 0.2 A. The radius of the coil is 0.02 m.

### Step-by-Step Solution:

1. **Calculate the Magnetic Field (B) inside the Solenoid:**
The magnetic field inside a solenoid is given by the formula:
\[
B = \mu_0 \cdot n \cdot I
...