9.1 The simplified sketch of an electric motor is shown below.
9.1.1 Write down the energy conversion that takes place in this motor. (1)
9.1.2 Is the motor above an AC motor or a DC motor? (1)
9.1.3 What is the function of the commutator in this motor? (1)
9.2 A resistor Y is rated 220 V, 100 W and is connected to a 220 V AC source, as shown in the circuit below.
9.2.1 Calculate the resistance of resistor Y. (3)
Another resistor Z with a rating 220 V, X W, is now connected in series to resistor Y and to the same AC source. See the diagram below.
The power dissipated by resistor Y changes to 80 W, while its resistance remains constant.
9.2.2 Calculate the power rating X of resistor Z, assuming that resistor Z has constant resistance. (6)
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