The earth's magnetic induction at a certain point is `7xx10^(-5) Wb/m^(2)`. This is to be annulled by the magnetic induction at the centre of a circular conducting loop of radius `5 cm`. The required current in the loop is

Options

A. `0.56 A`
B. `5.6 A`
C. `0.28 A`
D. `2.8 A`

Answer

B

Explanation

`(mu_(0))/(4pi)xx(2pi i)/r =Himplies ((10^(-7))xx2xx3.142xxi)/0.05=7xx10^(-5)`
`:. i=(7xx0.05xx10^(-5))/(2xx3.142xx10^(-7)) =35/(2xx3.142)=56 amp`