Permanent magnets

Yr 8

Like magnetic poles repel, unlike magnetic poles attract

A magnetic field as a space in which a permanent magnet or a conductor carrying an electric current experiences a force

The patterns of magnetic field lines around a bar magnet, a single wire and a solenoid

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Electromagnets

Yr 11

You must know how an electromagnet is constructed.

Uses of electromagnets, limited to a relay switch

[You will not be expected to draw the parts or circuits for an relay from memory but may be expected to interpret diagrams]

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Motor principle

Yr 11

The principle of a simple d.c. motor explained as an interaction between the magnetic force around a current carrying wire and an external magnetic field.

You must know how to use Fleming's left-hand rule to predict the direction of movement of a current-carrying wire in a magnetic field.

[Note: You will not be expected to draw the parts and circuits for a d.c. motor from memory but may be expected to interpret presented diagrams]

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Electromagnetic induction

Yr 11

Electromagnetic induction is the induction of a voltage and/or current when there is relative movement between a conductor and a magnetic field and when the magnetic field through a coil changes

Dynamo principle The dynamo principle is the production of a voltage and/or current in a coil when there is relative movement between it and a magnetic field

Use of generators in the production of mains electricity

[You will not be expected to draw the parts or circuits for an a.c. dynamo or generator]

You must know how to use the dynamo principle to explain the construction and performance of a.c. dynamos and generators.

a.c. and d.c.

Yr 11

A comparison of alternating current (a.c.) and direct current (d.c.), limited to

(i) differences in direction of current flow

(ii) differences in traces on a cathode ray oscilloscope (CRO)

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Transformers

Yr 11

1. A transformer is a device for stepping up or stepping down alternating voltages

2. The part played by transformers in the production and distribution of mains electricity

Construction of a transformer, limited to

(i) primary (input) coil (coil 1)

(ii) laminated iron core

(iii) secondary (output)coil (coil 2)

You will have to recall and use of the quantitative relationship

Transmission of electricity

Yr 11

Use of transformers and cables in the efficient distribution of electrical power over long distances

The principles and problems of power transmission, limited to

(i) high voltage

(ii) low current

(iii) thickness of cables

(iv) reduction of heat loss

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