Q.

A current of 30 A each flows in opposite directions in two conducting wires, placed parallel to each other at a distance of 8 cm. The magnetic field at the mid point between the two wires is ______ μT.     (μ04π=10-7 N/A2)                   [2026]

1 30  
2 300  
3 150  
4 0.1  

Ans.

(2)

Bnet=B1+B2=2×μ0i2πr=μ0iπr

Bnet=4π×10-7×30π×4×10-2=30×10-5T=300 μT