A long, straight wire is turned into a loop of radius 10 cm (see figure) If a current of 8 amperes is passed through the loop, then the value of the magnetic field and its direction at the centre C of the loop shall be close to

Options

A. `5.0 xx 10^(-5)` Newton (amp-meter) , upward
B. `3.4 xx 10^(-5)` Newton (amp-meter ) , upward
C. `1.6 xx 10^(-5)` Newton (amp-meter) , downward
D. `1.6 xx 10^(-5)` Newton (amp-meter) , upward

Answer

A

Explanation

`B = (mu_(0) I)/(2R) = (4pi xx 10^(-7) xx 8)/(2 xx 0.1)`
`= 5.024 xx 10^(-5)` N/Amp - meter (upward)