Two coils each of 100 turns are held at right angles such that one lies in the vertical plane with their centres coinciding. The radius of the vertical coil is 20 cm and that of the horizontal coil is 30 cm. How would you neutralize the magnetic field of the earth at their common centre ? What is the current to be passed through each coil? Horizontal component of earth's magnetic induction`=3.49 xx 10^(-5)` T and angle of dip = `30^@`

Explanation

To neutralize the magnetic field of the Earth at the common center of the two coils, we need to set up the coils such that the magnetic fields they produce counteract the Earth's magnetic field. We will calculate the current required in each coil to achieve this.

### Step-by-step Solution:

1. **Understanding the Given Data:**
- Number of turns in each coil (N) = 100
- Radius of the vertical coil (r1) = 20 cm = 0.2 m
- Radius of the horizontal coil (r2) = 30 cm = 0.3 m
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