The values of magnetic induction at two points on the axis of a bar magnet at a distance of 10cm - Physics - Magnetism And Matter

Question

The values of magnetic induction at two points on the axis of a bar
magnet at a distance of 10cm and 20cm respectively, from its centre
are in the ratio 25:2 Find the magnetic length of the magnet

Ujjval Chauhan · Accepted Answer

Dear student

The magnetic induction due to a bar magnet of magnetic moment M at a distance r fromthe centre of bar magnet on its axis is given by B=μo4π2Mrr2-l22r1=10 cmr2=20 cmB1B2=252μo4π2Mr1r12-l22μo4π2Mr2r22-l22=252r1r12-l22=252r2r22-l2210100-l22=25220400-l22400-l22=25100-l22400-l2=5100-l2400-l2=500-5l24l2=100l2=25l=5 cmso the magnetic length of the bar magnet =2l=10 cm

The values of magnetic induction at two points on the axis of a bar magnet at a distance of 10cm and 20cm respectively, from its centre are in the ratio 25:2. Find the magnetic length of the magnet.