A bar magnet of magnetic moment `10Am^(2)` has a cross sectional area of `2.5xx10^(-4)m^(2)` . If the intensity of magnetisation of the magnet is `10^(6)A//m`, then the length of magnet is

Options

A. 0.4 m
B. 0.04 cm
C. 0.04m
D. 50cm

Answer

C

Explanation

`M=10 Am^(2),A=2.5xx10^(-4)M^(2),`
`I=10^(6) A//m, l=?`
`I =(M)/(V)=(M)/(A.l)`
`therefore l=(M)/(AI)=(10)/(2.5xx10^(-4)xx10^(6))`