A coil wrapped around a toroid has inner radius of `10*0cm` and outer radius of `12*0cm`. If the wire wrapped makes `1100` turns and carries a current of `5A`, find the magnetic field (a) inside the core of the toroid (b) outside the toroid at a distance `10cm` from the other surface of toroid.

Explanation

Here, `r_1=10.0cm, r_2=12.0cm`, `I=5A`
Mean radius of toroid, `r=(10+12)/(2)=11.0cm=11xx10^-2m=0.11m`
Total length of toroid=circumference of toroid`=2pir=2pixx0.11=0.22pim`
total number of turns, `N=1100`
Number of turns per unit length will be, `n=(N)/(2pir)=(1100)/(0*22pi)m^-1`
(a) Magnetic field induction inside the core of the toroid,
`B=mu_0nI=(4pixx10^-7)xx(1100)/(0.22pi)xx5=0.01T`
(b) Magnetic field induction outside the toroid is zero because the field is only confined within the core of the toroid on which winding has been made.