A toroid has a core (non ferromagnetic material) of inner radius `25cm` and outer radius `26cm` around which 3500 turns of wire are wound. If the current in the wire is `11A`, what is the magnetic field (a) outside the toroid (b) inside the core of the toroid (c) in the empty space surrounded by the toroid?

Explanation

Inner radius of toroid, `r_(1)=25 cm =0.25 m`
Outer radius of toroid, `r_(2)=26 cm =0.26 m`
Number of turns N =3500
current in the wire, I=11A
The mean radius of toroid `r=((r_(1)+r_(2))/(2))=(2)/(2)(0.25+0.26)=0.51`
`therefore` length of toroid `=2pir =2pi xx0.51`
the magnetic field strength the due to toroid is `B=mu_(0) nI`
where n is number of turns per unit length
`n=(N)/(I)`
`B=4pixx10^(-7)xx(3500)/(pixx0.51)xx11=3.02xx10^(-2) T`