Solution

A copper ring has a radius of $4.0\,\mathrm{cm}$ and resistance of $1.0\,\Omega$. A magnetic field is applied over the ring, perpendicular to its plane. If the magnetic field increases from $0.2\,\mathrm{T}$ to $0.4\,\mathrm{T}$ in a time interval of $5 \times 10^{-3}\,\mathrm{s}$, what is the current in the ring during this interval?