Question

How many turns of wire would be needed around the core of nickel to get a magnetic field of 3.43 x 10-3T with a current of 800mA?

An electromagnet is created by wrapping 28 turns of copper wire around a 65cm long iron core. A current of 800mA is passed through the wire.

Answer 1

`N=(B.l)/(\mu i)=\frac{(3.43\times10^{-3}\quad T )(65\times10^[-2} \quad m)}{8.78\times10^{-5} \quad (Tm)/A\times0.8\quad A}=32 \quad turns`