Question

If a bar magnet of pole strength 'm' and magnetic moment 'M' is cut equally 5 times parallel to its axis and 4 tomes perpendicular to its axis then the pole strength and magnetic moment of each piece are respectively

• A. $\frac{n}{20},\frac{M}{20}$
• B. $\frac{n}{4},\frac{M}{20}$
• C. $\frac{n}{5},\frac{M}{20}$
• D. $\frac{n}{5},\frac{M}{4}$

Answer 1

The correct option is C $\frac{n}{5},\frac{M}{20}$

Given

Bar magnet of length L, pole strength m, magnetic moment M

It is cut 5 times parallel to axis and 4 times perpendicular to axis

Solution

When bar magnet is cut 5 times parallel to axis, then its pole strength become m/5

So new pole strength is m/5

When bar magnet is cut 4 times perpendicular to axis, then length of magnet become L/4

So new Magnetic moment will be M'=m/5*L/4

That is M'=M/20

The correct option is C