7.3 Induced Potential, Transformers and the National Grid Flashcards
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 ends 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 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
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
- the change is either the movement of the conductor or a change to the field
describe the makeup of a basic transformer.
a primary coil and a secondary coil of wire wrapped around an iron core.
what are two 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 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 a primary coil of a transformer be alternating?
- for current to be induced in the secondary coil, the magnetic field in the core must be continously changing
- for the magnetic field to be changing, the current in the priamry coild 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.
