Electromagnetic induction can create a voltage by movement of a conductor in a magnetic field. This voltage can make current flow. Transformers use electromagnetic induction to change the voltage of alternating currents.
What is another name for electromagnetic induction?
The motor effect
The generator effect
How can the direction of an induced potential be reversed?
By changing the direction of the magnetic field
By moving the magnet faster
By changing the direction of the magnetic field, and moving the magnet in the opposite direction
How is contact between the coil and circuit maintained in an alternator?
Slip rings and brushes allow continuous connection
The alternator can only complete one revolution and must then be rotated in reverse
A split ring commutator connects to each side for half a turn
What is the voltage from an alternator half a turn after maximum positive output?
Maximum negative output
Maximum positive output again
How can the voltage output from an alternator be doubled?
Reverse the direction of rotation
Double the speed of rotation
Halve the speed of rotation but reverse the direction of rotation
How can the voltage output from a dynamo be doubled?
In a dynamo, what is the function of the split ring commutator?
It reverses the coil connections every half turn, to keep the output current in the same direction all the time
It reverses the connections every half turn, to keep the output current alternating every half turn
It strengthens the magnetic field to make a greater output current for the same rotation speed
What is the function of a microphone?
It converts alternating current signals into direct current signals
It converts electrical signals into sound waves
It converts sound waves into electrical signals
How does a moving-coil microphone create electrical signals?
A magnet vibrates inside a coil of wire
A coil of wire vibrates in a magnetic field
An electromagnet vibrates inside a coil of wire
Why could a loudspeaker be said to be a reverse microphone?
They both use the motor effect
The both use the generator effect
A loudspeaker uses the motor effect and a microphone uses the generator effect