The earth's magnetic field at a given point is `0.5xx10^(-5) "Wb m"^(-2)` . This field is to be annulled by magnetic induction at the centre of a circular loop of radius 5 cm. The current required to be flown in the loop is nearly

Options

A. 0.2 A
B. 0.4 A
C. `4 A`
D. `40 A`

Answer

B

Explanation

As `B=(mu_0I)/(2R)=B_H`
`therefore I=(2B_H R)/mu_0 =(2xx0.5xx10^(-5)xx0.05)/(4pixx10^(-7))`= 0.3978 `approx` 0.4 A