The earth's magnetic field at a given point is `0.5xx10^(-5) Wb-m^(-2)`. This field is to be annulled by magnetic indcution at the centre of a circular conducting loop of radius `5.0 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

Magnetici field at the centre of circular loop
`B = (mu_(0))/(4pi) (2pi)/(r)`
`implies 0.5xx10^(-5) = (10^(-7)xx2xx3.14xx i)/(5xx10^(-2))`
`I = 0.4 A`