The distance between the poles of a horse shoe magnet is 0.1 m and its pole strength is 0.01 amp-m. The induction of magnetic field at a point midway between the poles will be

Options

A. `2xx10^(-5)T`
B. `4xx10^(-6)T`
C. `8xx10^(-7)T`
D. Zero

Answer

C

Explanation

Net magnetic field at mid-point `P, B=B_(N)+B_(S)`
where `B_(N)=` magnetic field due to N-pole
`B_(S)`= Magnetic field due to S-pole
`B_(N)=B_(S)=mu_(0)/(4pi)m/r^(2)`

`=10^(-7)xx0.01/(0.1/2)^(2)=4xx10^(-7)T`
`:. B_("net")=8xx10^(-7)T`.