Electromagnets Flashcards
What happens when u close the switch of a circuit?
The electric current flows around the circuit
What is produced when the current flows around conducting wire?
Magnetic field produced around wire
What do u use to prove there a magnetic field?
A compass
How can u tell if there’s a magnetic field or not with a compass?
When the current is off, compass needles lines up with the earths magnetic field. When current is on, compass deflects showing there is MF
What does the strength of the MF depend on?
The size of the current, larger current, stronger MF
How to check the direction of the field?
Right hand grip rule, Thumb faces way of conventional current, fingers show the way of the MF
What is another way to increase strength of field
Coil wire - solenoid and makes a strong and uniform MF inside the solenoid when current is on
3 ways to increase strength of MF from solenoid
1) increase size of current
2) increase the number of coil
3) place piece of iron inside solenoid called iron core
What is a solenoid containing and iron core called?
An electromagnet
Factors effecting force in motor effect
Magnetic flux density
Current
Length
How to determine direction of force
Fleming left hand rule -
First finger - direction of field (N-S)
Second finger - direction of current - + - -
Thumb - direction of force
What happens if conductor is parallel to magnetic field?
It will not experience a force
What is the electric motor (dc motor)
Made up of a coil between two permanent magnets
What happens if you put a loop of wire in a MF?
Will experience a force on both sides, one upwards one downwards, means loop will rotate in clockwise direction
What happens when loop is 90 degrees
It will stop rotating and if loop rotates beyond 90 then the forces will switch due to change in direction of current and forces it back to 90
How do u switch direction of the current?
Using a device - split ring commutator - split metal ring connecting to conducting bushes
What do the brushes do?
The brushes allow the electric current to pass onto the ring which produces a turning force on the motor. Force makes motor rotate clockwise and the current broken for a tiny fraction of a second but the wire keeps turning due to momentum. The current then switches direction and force goes back
Using a device
What is electromagnetism
An electric current moving through a conductor generating its own magnetic field
