Topic 7- 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 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 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 two ways that 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
