P7 - Magentism And Electromagnetism Flashcards
What is a permanent magnet?
Produces its own magnetic field
Where is magnetic field strongest?
At the poles of a magnet
What is an induced magnet?
A magnetic material that turns into a magnet when it’s put in a magnetic field.
What are 4 magnetic materials?
- Iron
- Steel
- Nickel
- Cobalt
What is a compass needle? And where does it point?
A small bar magnet
Points in the direction of the magnetic field it’s in.
Twisting a wire into a solenoid increases what around the wire?
The magnetic field strength
What is an electromagnet?
A solenoid with an iron core. It is a magnet that can be turned on and off.
Iron core = increases the magnetic field strength
Where are electromagnets used?
In fire alarm bells and in scrap yards to pick up large objects.
What is the motor effect?
When a magnet and a current - carrying conductor exert a force on each other.
What are three ways to increase the force?
- Increase the current
- Increase the magnetic field strength
- Increase the length of the conductor.
How was an electric motor work?
Direct current is passed through wire.
Each side of the coil experiences opposite forces.
Coil rotates.
How do loudspeakers and headphones work?
Alternating current is sent through coil.
Coil moves back and forth.
Paper cone moves back and forth.
Sound waves are created.
How do microphones work?
Sound waves hit diaphragm.
Diaphragm moves back and forth.
Coil of wire moves back and forth.
Alternating current is generated.
