A magnetic needle is arranged at the centre of a current carrying coil having 50 turns with radius of coil 20cm arranged along magnetic meridian. When a current of 0.5mA is allowed to pass through the coil the deflection is observed to be 30°. Find the horizontal component of earth's magnetic field

Explanation

To solve the problem, we need to find the horizontal component of the Earth's magnetic field (BH) using the given information about the current-carrying coil and the deflection of the magnetic needle.

### Step-by-Step Solution:

1. **Identify the given values:**
- Number of turns (n) = 50
- Radius of the coil (r) = 20 cm = 0.2 m
- Current (I) = 0.5 mA = 0.5 × 10^-3 A = 5 × 10^-4 A
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