A horizontal overheadpowerline is at height of `4 m` from the ground and carries a current of `100 A` from east to west. The magnetic field directly below it on the ground is
`( nu_(0) = 4 pi xx 10^(-7) Tm A^(-1)`

Options

A. `2.5 xx 10^(-7) T` northward
B. `2.5 xx 10^(-7)T` southward
C. `5 xx 10^(-6)T` northward
D. `5 xx 10^(_6)T` southward.

Answer

d

Explanation

Magnitude of magnetic field can be written as follows:
`B = (mu_(0)I)/(2 pi d) = (4 pi xx 10^(-7) xx 100)/(2 pi xx 4) = 5 xx 10^(-6) T`
If we align our right hand thumb from east to west pointing fingers downward then palm points towards south. Hence, option (d) is correct.