13.1-13.11-Electromagnetic induction Flashcards
How could you produce an electric current on a small scale?
.Spinning a coil of wire in between two permanent magnets will cause a current to flow in the wire
How could you produce an electric current on a small scale?
.In a thermal power station water heats up and evaporates to form steam
.The steam is put under pressure and forced into a turbine
.This causes the turbine to rotate which is connected to a massive coil of wire in a magnetic field
Give three factors that affect the size and voltage of the current produced
.Number of coils in wire
.Speed of rotation
.Magnetic field strength
How is electromagnetic induction used in alternators?
.To generate current which alters direction
How is electromagnetic induction used in dynamos?
.To generate direct current
What is the action of a microphone?
.Produce a current which is proportional to the sound signal
.Fixed magnet is at the centre and the coil around the magnet is free to move
.Pressure variations in the sound wave cause the coil to move, as it moves the current is induced in the coil (because it passes through the magnetic field)
.The current is then sent to a loudspeaker
Explain the actions of a loudspeaker
.Current flows into the coil .The magnetic field from magnet and current interact causing the coil to move .The cone therefore moves .Producing pressure variations .Making sound
What can alternating current induce?
It can induce another current in a circuit with a transformer
What can a transformer change?
The size of alternating voltage
Why in the national grid is electrical energy transferred at high voltage from power stations and then transferred at lower voltages in each locality for domestic uses?
.It improves the efficiency by reducing heat loss in transmission lines
What do step-up transformers do?
Increase the voltage
What do step-down transformers do?
.Decrease the voltage
What does the power of a primary circuit equal?
The power in secondary
