Topic 13: Electromagnetic Induction Flashcards
What is electromagnetic induction?
When a wire is moved across a magnetic field, a current is produced
When does induction occur?
If a magnet is moved in a coil of wire or if a coil of wire rotates in a magnetic field
What are generators?
A device that converts mechanical energy into electrical energy, it’s the opposite of an electric motor
How do AC generators work?
As the coil rotates past the vertical the sides of the coil move through the magnetic field in opposite directions to before
How can the size of an induced current be increased?
- increase the speed at which the coil rotates
- increase the strength of the magnetic field
- increase the number of turns in the coil
What’s an alternating current?
Currently that constantly changes direction, produced by most electrical generators
What’s a commutator?
The part of a motor that enables the coil to rotate using direct current
What’s the direct current?
Occurrent that always flows in the same direction, produced by cells and batteries
What’s a motor?
A device that converts electrical energy into mechanical energy
What are slip rings?
The parts of a generator that enable the rotating coil to produce alternating current
What is the structure 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’s easily magnetised
How does a transformer work?
-an alternating current flows through the primary coil
-this introduces a changing magnetic field in the core
-this changing magnetic field induces an EMF which produces a current in the secondary coil
When a step down transformer does the secondary coil have more or fewer turns?
The secondary coil has fewer turns
What is an advantage of a step down transformer in the National Grid?
It means that the voltage can be reduced to a value safe enough to be used in houses (230V)
