State what is meant by a magnetic field 

a region in which a magnetic pole experiences a force 

State what is meant by the direction of a magnetic field 

the direction of the force on the N pole of a magnet at that point 

State the factors that increase the emf induced in electromagnetic induction 

Move wire faster 

Stronger magnetic field 

Greater length of wire / more turns on coil 

State the factors which increase the rate of rotation of a motor 

Greater current 

Stronger magnetic field 

More turns on the coil 

Explain the purpose of a split ring commutator in a motor 

To reverse the direction of current in the coil every half turn 

So that the motor continues to spin in the same direction 

What is meant by a step-up transformer? 

More turns on secondary coil than primary coil 

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

Alternating current in the primary coil produces an alternating magnetic field in the core 

The core channels the field to the secondary coil 

The alternating magnetic field in the secondary coil induces an alternating emf in the secondary coil 

State the advantages of high-voltage transmission 

High voltage transmission requires lower current for the same power 

This means the energy lost in the resistance of the cables is much reduced