Two concentric circular coils X and Y of radii 16 cm and 10 cm respectively, lie in the same vertical plane containing the north to south direction. Coil X has 20 turns and carries a current of 16A, coil Y has 25 turns and carries a current of 18A. The direction of the current in X is anticlockwise and is clockwise in Y, for an observer looking at the coils facing west. Give the magnitude and direction of the net magnetic field due to the coils at their centre.

Explanation

Given : `N_(1)=20, I_(1)=16A, R=0.16m`

`" "B_(s)=mu_(0)/(4pi)(2piN_(1)I_(1))/(R_(1))=(10^(-7) times 2 times 3.142 times 20 times 16)/(0.16)`
`" "B_(s)=1.257 times 10^(-3)T` pointing east.
`N_(2)=25, I_(2)=18A, R=0.10m.`
`therefore " "B_(y)=(10^(-7) times 2 times 3.142 times 25 times 18)/(0.10)`
`" "B_(y)=2.828 times 10^(-3)T` pointing west.