Question 2
A long straight wire carries a current of 35 A. What is the magnitude of the field B at a point 20 cm from the wire?
Current in the wire, I = 35 A
Distance of a point from the wire, r = 20 cm = 0.2 m
The magnitude of the magnetic field at this point is given as:
B 
Where,
μ0= Permeability of free space = 4π × 10-7 T m A-1
Hence, the magnitude of the magnetic field at a point 20 cm from the wire is 3.5 × 10-5 T.
