A deflection megnetometer is placed with its arms in north-south direction. How and where should a short magnet having `M/B_H = 40 A m^2 T(-1)` be placed so that the needle can stay in any position?

Explanation

To solve the problem, we need to determine how and where to place a short magnet so that the deflection magnetometer needle can remain in any position. The given ratio \( \frac{M}{B_H} = 40 \, \text{A m}^2/\text{T} \) is crucial for our calculations.

### Step-by-Step Solution:

1. **Understand the Setup**:
The deflection magnetometer is oriented with its arms in the north-south direction. This means that the magnetic field of the Earth will act along this direction.

2. **Identify the Parameters**:
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