Define the tesla in terms of the force on a current-carrying conductor in a magnetic field.
A long solenoid has a cross-sectional area of $28\\,\\text{cm}^2$, as shown in Fig. 5.1. Coil C, made from 160 turns of insulated wire, is wound tightly around the middle of the solenoid. The magnetic flux density $B$ at the centre of the solenoid is given by $B = \\mu_0 n I$, where $I$ is the current in the solenoid, $n$ is a constant equal to $1.5 \\times 10^{3}\\,\\text{m}^{-1}$ and $\\mu_0$ is the permeability of free space. Calculate the magnetic flux density at the centre when the current in the solenoid is $3.5\\,\\text{A}$.
Calculate the flux linkage in coil C.
State the law of electromagnetic induction given by Faraday.
In (b), the current in the solenoid is reversed direction in $0.80\\,\\text{s}$. Calculate the average e.m.f. induced in coil C.