induced potential, transformers & the national grid

what happens when an electrical conductor moves relative to a magnetic field?

a potential difference is induced across the ends of the conductor

what happens to an electrical conductor when there is a change to the magnetic field that it is placed in?

a potential difference is induced across the end of the conductor

what is the requirement for an induced potential difference to cause a current flow?

the conductor must form a closed loop or be part of a complete circuit

what can be said about the direction of the magnetic field produced by an induced current?

• the direction of the field is such that it opposes the change that induced the current

• this change is either the movement of the conductor or a change to the field

what are 2 ways that the generator effect is used to generate different types of current?

• in an alternator to produce alternating current

• in a dynamo to produce direct-current

what electromagnetic effect does a microphone take advantage of and how?

• the generator effect

• it converts the pressure variations in sound waves into alternating current in a circuit

describe the ,makeup of a basic transformer

a primary coil and a secondary coil of wire wrapped around an iron core

why is iron used as the core for a transformer?

it is easily magnetised

explain how a transformer works

• an alternating current flows through the primary coil

• this induces a changing magnetic field in the core

• this changing magnetic induces a current to flow in the secondary coil

why must the current flowing through the primary coil of a transformer be alternating?

• for current to be induced in the secondary coil, the magnetic field in the core must be continuously changing

• for the magnetic field to be changing, the current in the primary coil must be alternating

what can be said about the electrical power input and output of a 100% efficient transformer?

the electrical power input is equal to the electrical power output