Question

A short bar magnet is pulled rapidly through a conductind cooil along its axis with uniform velocity, with its north pole entering the coil first. Sketch vartition of (a) flux, (b) induced current and (c) power dissipated in coil with time.

Answer 1

Magnetic field due to magnet
`B=(mu_(0))/(4pi).(2M)/(x^(3))`
`Bprop(1)/(x^(3)` , `phiprop(1)/(x^(3))`
Flux increases, reaching to a maximum value and then decreases.
Induced current `v//s` time `t` :
When flux increases, north pole is formed, current is anticlockwise.
When flux decreases, south pole is formed, current is clockwise. Taking anticlockwise current as positive.