The diagram shows an incomplete series circuit designed to control a cooling fan (represented by the motor, M).
(i) Draw a thermistor in the gap to complete the circuit.
(ii) Add a voltmeter to the circuit to measure the voltage across the motor.
The voltmeter measures a voltage of 7.2 V across the motor. The ammeter measures a current of 180 mA. (i) State the equation linking voltage, current, and resistance.
(ii) Calculate the electrical resistance of the motor.
The completed circuit is moved from a cold environment near an ice pack into a warm room. Explain how this temperature change would affect the speed of the motor.
State how the current in the circuit would change if an identical second motor is added in series with the first motor.
