Producing Electricty Flashcards
What is a magnetic field?
The space around a magnet in which a magnetic force acts.
Where is the magnetic field strongest?
When the field lines are closest together.
When is the voltage induced?
When a magnet is moved near a piece of wire: piece of wire is part of a circuit, current will flow.
When is the voltage always induced?
When there is relative movement between a magnet and a coil of wire.
When is the direction of the current reversed?
When the motion of the wire is reversed, or the magnet is turned round.
When does the current increase?
If the speed of motion increases, a stronger magnet is used or there are more turns of wire in the coil.
When is there a continuous supply of electricity?
When there is a continuous relative motion between a magnet and a coil of wire.
What is electromagnetic induction?
When the coils of wire continuously ‘cut’ the magnetic field lines so a voltage is induced.
A larger voltage is induced if:
- the strength of the magnet is increased
- number of turns in the coil is increased
- an iron core is used inside the coil
- the rate at which the coil is turned is increased.
What happens when the rate of the cutting field lines increases?
The larger the induced voltage.
Where is the mains electricity produced?
By generators in power stations that induce an alternating voltage.
As a coil rotates in a uniform magnetic field it cuts the lines of magnetic field at different rates:
- the coil is at a right angles to the fold lines:cuts no field lines: induced voltage is zero
- the coil is parallel to the field lines, it’s rate of cutting field lines is at a maximum, so the induced voltage is at a peak
- as coil rotates, it cuts field lines in a different direction: voltage alternates.
What always flows in the same direction?
Direct current (d.c)
What changes direction at regular intervals?
Alternating current (a.c)
What is the voltage of the U.K. mains electricity?
A.C and generated at 230V and frequency at 50Hz.
