Question

A transmission line carries a current of 100 A. in east to west direction. Find magnitude of the magnetic field due to current at a distance 1m below the wire:
(a)
2 × 10–5 T

(b)
2 × 10+5 T

(c)
105 T

(d)
10–5 T

Answer 1

B=\[\mu\]I/(2piR)(For an infinitely long wire)
=(4pi/10^7*100)/(2pi*1) (\[\mu\]=4pi/10^7)
=2*10^-5T