1. A step-down transformer in a mobile phone charger converts 230 V mains into 5 V. The phone needs a current of 3 A when charging. What current is required from the mains?
2. How can you double the output voltage of a dynamo?
Double the speed of the rotation
3. Why is it possible to convert a microphone into a loudspeaker?
Because a loudspeaker uses the motor effect and a microphone uses the opposite, the generator effect.
4. What is the purpose of a split ring commutator ina dynamo?
The split ring commutator reverses the coil connections every half turn, to keep the output current in the same direction all the time.
5. What is another name for electromagnetic induction?
The generator effect
6. Electrical energy can be measured in?
7. Define the motor effect
If a wire carrying a current is placed in a magnetic field a force is produced.
8. Explain what is meant by an alternating voltage.
The changing of polarity
9. What does the term 'electromagnetic induction' mean?
The generating of electricity, by the movement of a magnetic field and a wire.
10. What is the voltage of the mains electricity in UK houses?