14.1 Electromagnetic induction
1. Describe an experiment that shows that a
changing magnetic field can induce an e.m.f. in a
2. State the factors affecting the magnitude 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.
1. Describe the construction of a basic iron-cored
transformer as used for voltage transformations.
2. Recall and use the equation
(Vp / Vs) = (Np / Ns)
3. Describe the use of the transformer in highvoltage transmission of electricity.
4. Recall and use the equation
Vp Ip = Vs Is
(for 100% efficiency).
5. Explain why energy losses in cables are lower
when the voltage is high.
14.4 The magnetic effect of
1. Describe the pattern of the magnetic field due
to currents in straight wires and in solenoids.
2. Describe the effect on the magnetic field of
changing the magnitude and direction of the
3. Describe applications of the magnetic effect of
current, including the action of a relay.
14.5 Force on a currentcarrying conductor
1. Describe and interpret an experiment to show
that a force acts on a current-carrying conductor
in a magnetic field, including the effect of
• the current
• the direction of the field.
2. State and use the relative directions of force,
field and current.
14.6 D.C. motor
1. Describe the turning effect on a currentcarrying coil in a magnetic field.
2. Relate this turning effect to the action of an
3. Describe the effect of increasing (a) the
number of turns in the coil (b) the current.