Two small magnets are placed horizontally perpendicular to magnetic meridian. Their north poles are at `30cm` east and `20cm` west from a compass needle. Compare the magnetic moments of the magnets, if compass needle remains undeflected.

Answer

`8:27`

Explanation

The compass needle at C lise on axial line of two magnets, figure. As it remains undeflected, therefore, fields due to two magnets must be equal and opposite.

`B_1=B_2`
`(mu_0)/(4pi)xx(2M_1)/(d_1^3)=(mu_0)/(4pi)(2M_2)/(d_2^3)`
`(M_1)/(M_2)=(d_1/d_2)^3=(20/30)^3=8:27`