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.

Answer 1

First, let's decide on the standard paper directions.

Magnitude of magnetic field,

`|vecB| = μ_0/(4pi) (2"I")/r`

= `10^-7 xx (2 xx 50)/2.5`

= 40 × 10^-7 T

The direction of the magnetic field is upwards when one uses the right hand palm rule.

`vecB = 40 xx 10^-7  hatk`T