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 .

Explanation

`I= 50 A, r = 2.5 m`
`B = (mu_0 I)/(2 pi r) = (4pi xx10^(-7) xx 50)/(2 pi xx 2.5) = 4 xx 10^(-6) T` upwards , (due to the wire alone)