ME6 - Electromagnetic induction Flashcards
What is electromagnetic induction?
The creation of a voltage in a wire which is experiencing a change in magnetic field
What is the dynamo effect?
Transforming kinetic energy into electrical energy (in a power station this kinetic energy is provided by turbines)
How can you get EM induction?
- When an electrical conductor moves through a magnetic field (cutting the magnetic field lines) causing the electrical conductor changes
How can you test EM induction?
By connecting an ammeter to a conductor and moving the conductor through a magnetic field - it will show the magnitude and direction of the induced current
What happens if the direction of movement is reversed?
The induced voltage/current will be reversed too
What three things can you increase to get a bigger voltage?
- The strength of the magnet
- The number of turns on a coil
- The speed of the movement
What is the difference between a simple electric motor and a generator?
Motor - you have a current in the wire and magnetic field which causes movement
Generator - You have a magnetic field and movement which induces a current
What does AC generators do?
They rotate a coil in a magnetic field which produces a current
What is there construction similar to?
A motor
What happens as the coil spins?
A current is induced in the coil. The current changes direction every half turn
What do generators have instead of a split-ring commutator?
Slip rings and brushes to the contact doesn’t swap every half turn
What do CRO displays show?
An ac voltage - the faster the revolutions produce more peaks and higher overall voltage
How do power stations use ac generators?
They produce electricity - they get the energy needed to turn the coils or magnetic field in different ways
A magnet is held above a coil. The coil is connected to a voltmeter. The magnet is released and falls into the coil
Explain why the voltmeter records a reading
As the magnet falls through the coil, there is a changing magnetic field acting on the coil. This inducers a voltage across the coil and a current through it
The magnet is released from a greater height. How does this affect the voltmeter. Explain your answer
The magnet will be moving faster so the induced voltage will be greater