Download P14 Electromagnetic effects CAN YOU

P14 Electromagnetic effects
Can you……?
14.1 Electromagnetic induction
1 Describe an experiment that shows that a changing magnetic field can induce an e.m.f. in
a circuit.
2 State the factors affecting the size of an induced e.m.f.
14.2 a.c. generator
1 Describe a rotating-coil generator and the use of slip rings.
2 Sketch a graph of voltage output against time for a simple a.c. generator.
14.3 Transformer
1 Name the parts of a transformer
2 Remember and use the equation Vp/Vs = Np/Ns
3 Describe the use of the transformer in high-voltage transmission of electricity.
4 Remember and use the equation VpIp = VsIs (for 100% efficiency).
5 Explain why energy losses in cables are lower when the voltage is high.
14.4 The magnetic effect of a current
1 Describe the pattern of the magnetic field around a straight wires and in solenoids (coils).
2 Describe the effect on the magnetic field of changing the size and direction of the current.
3 Describe how an electric bell and relay work.
14.5 Force on a current-carrying conductor
1 Describe an experiment to show that a force acts on a current-carrying wire in a magnetic
field.
2 Use Fleming’s left-hand rule to predict the directions of force, field or current.
14.6 d.c. motor
1 Describe the turning effect on a current-carrying coil in a magnetic field.
2 Relate this turning effect to the action of an electric motor.
3 Describe the effect of increasing (a) the number of turns in the coil (b) the current.
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