A long straight wire in the horizontal plane carries a current of 50 A in north to south direction.

Question

A long straight wire in the horizontal plane carries a current of 50 A in north to south direction. Give the magnitude and direction of B at a point 2.5 m east of the wire.

Professor PC Thomas Classes · Answer

$B = \frac{\mu_0 I}{2\pi r} = \frac{4\pi 	imes 10^{-7} 	imes 50}{2\pi 	imes 2.5} = 4.0 	imes 10^{-6}	ext{ T}$. Using the Right-Hand Grip Rule, the direction is vertically upward.