Electromagnetism

Describe the forces between magnetic poles and between magnets and magnetic materials, including the use of the terms north pole (N pole), south pole (S pole), attraction and repulsion, magnetised and unmagnetised

Describe induced magnetism

State the differences between the properties of temporary magnets (made of soft iron) and the properties of permanent magnets (made of steel)

State the difference between magnetic and non-magnetic materials

Describe a magnetic field as a region in which a magnetic pole experiences a force

Draw the pattern and direction of magnetic field lines around a bar magnet

State that the direction of a magnetic field at a point is the direction of the force on the N pole of a magnet at that point

Describe the plotting of magnetic field lines with a compass or iron filings and the use of a compass to determine the direction of the magnetic field

Describe the uses of permanent magnets and electromagnets

Explain that magnetic forces are due to interactions between magnetic fields

Know that the relative strength of a magnetic field is represented by the spacing of the magnetic field lines

Know that a conductor moving across a magnetic field or a changing magnetic field linking with a conductor can induce an e.m.f. in the conductor

Describe an experiment to demonstrate electromagnetic induction

State the factors affecting the magnitude of an induced e.m.f.

Know that the direction of an induced e.m.f. opposes the change causing it

State and use the relative directions of force, field and induced current

Describe a simple form of a.c. generator (rotating coil or rotating magnet) and the use of slip rings and brushes where needed

Sketch and interpret graphs of e.m.f. against time for simple a.c. generators and relate the position of the generator coil to the peaks, troughs and zeros of the e.m.f.

Describe the pattern and direction of the magnetic field due to currents in straight wires and in solenoids

Describe an experiment to identify the pattern of the magnetic field (including direction) due to currents in straight wires and in solenoids

Describe how the magnetic effect of a current is used in relays and loudspeakers and give examples of their application

State the qualitative variation of the strength of the magnetic field around straight wires and solenoids

Describe the effect on the magnetic field around straight wires and solenoids of changing the magnitude and direction of the current

Describe an experiment to show that a force acts on a current-carrying conductor in a magnetic field, including the effect of reversing: (a) the current (b) the direction of the field

Recall and use the relative directions of force, magnetic field and current

Determine the direction of the force on beams of charged particles in a magnetic field

Know that a current-carrying coil in a magnetic field may experience a turning effect and that the turning effect is increased by increasing: (a) the number of turns on the coil (b) the current (c) the strength of the magnetic field

Describe the operation of an electric motor, including the action of a split-ring commutator and brushes

Describe the construction of a simple transformer with a soft-iron core, as used for voltage transformations

Use the terms primary, secondary, step-up and step-down

Recall and use the equation Vp Np Vs = Ns where p and s refer to primary and secondary

Describe the use of transformers in high- voltage transmission of electricity

State the advantages of high-voltage transmission

Explain the principle of operation of a simple iron-cored transformer

Recall and use the equation for 100% efficiency in a transformer IpVp = IsVs where p and s refer to primary and secondary

Recall and use the equation P = I2R to explain why power losses in cables are smaller when the voltage is greater