A coil P of N turns is made from a length L of wire. The coil carries a current I when between two magnetic poles. A similar coil Q of 2N turns is made from a length 2L of identical wire. It also carries a current I when between the two magnetic poles. Which coil has the greater resistance and which coil experiences the greater turning effect?

Which properties make materials suitable for use as a core in an electromagnet?

A long flexible wire is wrapped round two wooden pegs. A large current is passed in the direction shown. Which two pa…

The diagram shows a d.c. motor. Why is a split-ring commutator used?

Using an electric kettle, 200 g of water at 100 °C is converted into steam at 100 °C in 300 seconds. The specific lat…

When a gas in a container of fixed volume is heated, the pressure of the gas increases. Which statement explains this?

A ripple tank is used to show wave behaviour. The dipper vibrates up and down at a constant frequency. What happens t…