A long, vertical straight wire carrying a current of 30 A is placed in an external, uniform magnetic field of (`4.0 xx (10^-4)` T exists from south to north. Find magnetic field at a point 2.0 away from the wire.

Explanation

To solve the problem, we need to calculate the magnetic field at a point 2.0 cm away from a long vertical wire carrying a current of 30 A in the presence of an external magnetic field of \(4.0 \times 10^{-4}\) T directed from south to north.

### Step-by-Step Solution:

1. **Identify the Given Values:**
- Current, \(I = 30 \, \text{A}\)
- Distance from the wire, \(D = 2.0 \, \text{cm} = 0.02 \, \text{m}\)
- External magnetic field, \(B_{ext} = 4.0 \times 10^{-4} \, \text{T}\)
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