Question

Two circular loops of radii r and 2r have currents I and `I//2` flowing through them in clockwise and anticlockwise sense respectively. If their equivalent magnetic moments are `M_1` and `M_2`, what is the relation between `M_1` and `M_2`?

Answer 1

`M_1=I(pir^2)`
`M_2=I/2(pi4r^2)=I(2pir^2) :. M_1/M_2=1/2`
The direction of `vecM_1` is opposite to the direction of `vecM_2`.