Topic 7-Magnestism and electromagnetism Flashcards
What are the two poles?
North and south.
What do all magnets produce?
A magnetic field.
Where is the magnetic field strongest on a magnet?
At the poles.
The closer magnetic field lines are …
The stronger the magnetic field.
Which direction do magnetic field lines always go?
From north to south.
What forces can magnets experience?
Attraction or repulsion.
North and a North?
Repulsion.
South and a North?
Attraction.
What device shows the direction of magnetic field lines?
A compass.
What are the two types of magnets?
Permanent and induced.
What is a permanent magnet?
A magnet that can produce its own magnetic field.
What are induced magnets?
Magnetic materials that turn into a magnet when they are put into a magnetic field.
What is the force between permanent and induced magnets?
Attraction.
What happens when a current flows through a wire?
A magnetic field is created around the wire.
How can you increase the strength of the magnetic field that a wire produces?
By wrapping the wire into a coil.
What is the coil called that you wrap around a wire to increase the magnetic field?
A solenoid.
What is a solenoid with an iron core called?
An electromagnet.
What can electromagnets be used for?
To pick stuff up with a crane.
What is the equation for force?
Magnetic flux density x current x length.
What is the generator effect?
The induction of a potential difference in a wire which is moving relative to a magnetic field, or experiencing a change in magnetic field.
What does the generator effect create?
A potential difference in a conductor.
If the conductor is part of a circuit what does the generator effect create?
A current.
what do dynamos generate?
A direct current.
What do alternators generate?
An alternating current.
How do microphones work?
By generating a current from sound waves.
What type of current do transformers only work with?
An alternating current.
What two types of coil do transformers have?
Primary and secondary.
What are the two coils joined together with in a transformer?
An iron core.
What are the two types of transformers?
Step up transformers and step down transformers.
What do step up transformers have to increase the potential difference?
More turns on the secondary coil than the primary coil.
What do step down transformers have to decrease the potential difference?
More turns on the primary coil than the secondary coil.
