Electromagnetism Flashcards
Motor effect
Current-carrying conductor is placed in a magnetic field, and is going to experience a force. In order to experience the force, current flow and field cannot be parallel.
Factors affecting magnetic force
Current: higher the current=higher force
Magnetic field: stronger the field=higher the force
Angle between field and direction of current:
Rule used for motors
Left hand rule
F force
B magnetic field
I current
Motors convert…
Electrical energy into Kinetic
Reversing direction of current or direction of magnetic field….
Reverses direction of force
The forces make the coil rotate and the speed of the rotation can be increased by:
-increasing current
-using a stronger magnet
-bringing poles of the magnet closer together
Electromagnetic induction:
If a conductor moves in a magnetic field, an emf is induced.
Generators convert:
Kinetic energy into electrical energy.
Why?
Because the moving magnet transfers energy thus electricity is being created.
Factors affecting induced emf:
Increases if:
-more turns
-magnet or conductor moves faster
-stronger magnet
-magnetic field lines are perpendicular to magnet
Rule used for gene”right”ors
Flemings RIGHT hand rule
thuMb: Motion
First finger: Force
seCond: Current
Lenz’s Law
The induced (created) emf (voltage) will oppose the charge inducing it. ENERGY HAS TO BE CONSERVED
Transformers
Have primary circuits and secondary circuits
PRIMARY CIRCUIT: Vp (primary voltage), Ip (primary current), Np(numbers of turns in primary circuit)
SECONDARY CIRCUIT: Vs, Is,Ns
How do transformers work?
1) An alternating voltage in the primary circuit (Vp) generates an alternating current (Ip). This current will produce and alternating magnetic field.
2) The changing magnetic field travels through the secondary circuit through the iron core.
3) An alternating emf (Vs) is induced in a secondary circuit.
4) IN A CLOSED CIRCUIT, an alternating current will follow.
Transformer equation:
Vp/Vs= Np/Ns
IpVp=IsVs
Np> Ns
Step-down transformer
