A long, straight wire carrying a current of 30 A is placed in an external, uniform magnetic field of `4.0 xx 10^-4` T exists from south to north.Find at a point 2.0 away from the wire.

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_(2)^(2))=5xx10^(-4)T`