A large coil has a smaller coil inserted inside it so that their axes are parallel. The smaller coil has $200$turns and a diameter of $2.0 \mathrm{cm}$. A changing current in the large coil causes the magnetic field to be increasing at a rate of $0.45 \mathrm{T} {\mathrm{s}}^{-1}$. Calculate the emf induced in the smaller coil.

Look at the diagram. The rod AB is free to move. The magnetic field is increasing. Determine what will happen to the rod AB.

Two identical rings made out of conducting material are released from rest, from the same height above the ground. One ring will fall through a region of a horizontal magnetic field. State and explain which ring will reach the ground first, given that they are released at the same time.

A $300 \mathrm{MW}$power station produces electricity at $80 \mathrm{kV}$, which is then supplied to consumers along with cables of total resistance $5.0 \mathrm{\Omega }$. What percentage of the produced power is lost in cables?

A $300 \mathrm{MW}$power station produces electricity at $80 \mathrm{kV}$, which is then supplied to consumers along with cables of total resistance $5.0 \mathrm{\Omega }$. What percentage of the produced power will lost in the cables if the electricity is produced at$100 \mathrm{kV}$?

The rms voltage output of a generator is $220 \mathrm{V}$. The coil is square of side $20.0 \mathrm{cm}$, has $300$ turns of wire and rotates at $50$revolutions per second. What is the magnetic field? 

The graph shows the variation, with time, of the magnetic flux linkage through a loop. What is the rms value of the emf produced in the loop?

A power station produces$150 \mathrm{kW}$ of power, which is transmitted along cables of total resistance $2.0 \Omega$. What percentage of the power is lost if it is transmitted at $1000 \mathrm{V}$.

A power station produces$150 \mathrm{kW}$ of power, which is transmitted along cables of total resistance $2.0 \mathrm{\Omega }$. What percentage of the power is lost if it is transmitted at $5000 \mathrm{V}$.