P5.4 Flashcards
What is mains electricity produced by?
Generators
What do generators produce?
A voltage by the process of electromagnetic induction
What can a changing magnetic field caused by changes in the current increase he coil of wire induce?
A voltage in the neighbouring coil
What will a changing current in one coil of a transformer cause?
What in turn does this induce?
A changing magnetic field in the iron,which in turn will induce a changing PD across the other transformer coil
What can transformers change the size of?
An alternating voltage
Voltage across secondary coil
=
Number of turns in a secondary coil
What happens when a magnet is moving into a coil of wire?
A voltage is induced across the ends of the coil
If the magnet is moving out of the coil,or the other pole of the magnet is moving into it,there is a ……
Voltage induced in the opposite direction
If the ends of the coil are connected to make a closed circuit,what happens to the current?
The current will flow round the circuit
In a generator,a magnet or electromagnet is rotated within a coil of wire to induce what?
A voltage across the ends of the coil
The size of this induced voltage can be increased by (4 points)
- increasing the speed of rotation of the magnet/electromagnet
- increasing the strength of its magnetic field
- increasing the number of turns on the coil
- placing an iron core inside the coil
When the current is always in the same direction,it is a what?
E.g-
Direct current (d.c) E.g the current from a better
Mains electricity is what?
A a.c supply
Why is an a.c used?
Because it is easier to generate than d.c and is simpler to distribute over long distances
What is the mains domestic supply in the U.K.?
230 volts
