Two circular coils are made from a uniform wire the ratio of radii of circular coils are `2:3 &` no. of turns is `3:4` . If they are connected in parallel across a battery.
`A:` Find ratio of magnetic inductions at their centres
`B:` Find the ratio magnetic moments of 2 coils.

Explanation

When connected in parallel
`a) Balpha(1)/(r^(2)),(B_(1))/(B_(2))=((r_(2))/(r_(1)))^(2)=((3)/(2))^(2)=(9)/(4)`
`b)M=niA_(coil)`but`i=(V)/(R)=(V)/(rhol)A_(wire)`
`impliesM=(Va_(wire))/(rho(2pir_(coil))),M=(VA_(wire))/(rhoX2)r_(coil)`
`(M_(1))/(M_(2))=(r_(1))/(r_(2))=(2)/(3)`.