First 291 words of the document:
How can electricity be used to make things move?
When conductor is put in magnetic field it may experience a force
The size of force can be increased by;
Increasing strength of magnetic field
Increasing size of current
The conductor will not experience a force if it is parallel to magnetic field
Direction of force is reversed if;
Direction of current reversed
Direction of magnetic field reversed
How do generators work?
If electrical conductor passes through magnetic field lines an electrical potential different is
induced across the ends of the conductor
If a magnet is moved into a coil of wire an electrical potential difference is induced across the
ends of the coil
If wire is part of complete circuit a current is induced in the wire
If direction of motion or polarity of magnet is reversed the direction of induced potential
difference and induced current is reversed
Generator effect occurs if magnetic field is stationary and coil is moved
Size of induced potential difference increases when;
Speed of movement increases
Strength of magnetic field increases
Number of turns of coil increases
Area of coil is greater
How do transformers work?
Alternating current in primary coil produces changing magnetic field in iron core so in
secondary coil. This induces alternating potential difference across ends of secondary coil
P.d across primary/p.d across secondary = number of turns on primary/number of turns on
Step-up transformer, pd across secondary coil is greater than primary coil.
Step-down transformer, pd across primary coil is greater than secondary coil.