A long straight wire carries a current of 35 A. What is the magnitude of the field B at a point 20 cm from the wire?

Explanation

`B = ( mu _(0))/( 4pi) xx (2 I )/(a) = (10 ^(-7) xx 2 xx 35)/( 2 0 xx 10 ^(-2)) = 3. 5 xx 10 ^(-5)T`