P7 - Magnetism and Electromagnetism Flashcards
What is a magnetic field? In what direction do they point?
A region where other magnets or magnetic materials experience a non-contact force.
They always go from north to south.
What are permanent magnets?
Magnets that produce thier own magnetic field.
What are induced magnets?
Induced magnets are magnetic materials that turn into a magnet when they’re put into a magnetic field.
Describe the magnetic field around a current-carrying wire.
The field is made up of concentric circles perpendicular to the wire, with the wire in the centre.
What is a solenoid?
A solenoid is a coil of wire - if you wrap a wire into a coil, it will strengthen the magnetic field.
What is an electromagnet?
An electromagnet is a magnet whose magnetic field can be turned on and off with an electric current.
What is the motor effect?
When a current-carrying wire is put between magnetic poles, the field around the wire interacts with the field of both magnetic poles - this causes the magnet and conductor to exert a force on eachother, causing the wire to move.
Name two ways to increase the force of a wire.
Increase the strength of magnetic field.
Increase the amount of current passing through conductor.
How can you find the size of a force acting on a conductor in a magnetic field?
Force (N) = Magnetic flux density (tesla) x Current x Length (m)
How do you find the direction of a force?
Fleming’s left-hand rule ;
thuMb = Motion
First Finger = Field
seCond finger = Current
