A long straight wire carrying current of `30 A` is placed in an external uniform magnetic field of induction `4xx10^(4) T`. The magnetic field is acting parallel to the direction of current. The magnitude of the resultant magnetic inuduction in tesla at a point `2.0 cm` away form the wire is

Options

A. `10^(-4)`
B. `3xx10^(-4)`
C. `5xx10^(-4)`
D. `6xx10^(-4)`

Answer

C

Explanation

`B_(1) = 4xx10^(-4) T`

`B_(2) = 10^(-7) xx (2xx30)/(2xx10^(-2)) = 3xx10^(-4) T`
`:. B_(net) = sqrt(B_(1)^(2) + B_(1)^(2)) = 5xx10^(-4) T`