A bar magnet of length 3cm has points `A` and `B` along its axis at distance of `24cm` and `48cm` on the opposite sides. Ratio of magnetic field at these points will be

Options

A. `8`
B. `1//2 sqrt(2)`
C. `3`
D. `4`

Answer

A

Explanation

Both points A and B lying on the axis of the magnet and on axial position
`B prop 1/d^(3) implies B_(A)/B_(B)=(d_(B)/d_(A))^(3)=(48/24)^(3)=8/1`