Physics IGCSE Flashcards
Why will E.M.F induce?
If there is movement between conductor and MF
Also if conductor is stationary in changing MF
conductor cuts through wire if perpendicular.
What is Lenz’s Law
Direction of induced potential difference always opposes change that produces it
Tries to stop wire or magnet from moving
Factors affecting EM imduction size
- speed in which wire is moved
- size of coil
- strength of magnetic field
What is an AC generator
Type of generator that converts mechanical energy into electrical energy in form of alternating current
Slip Rings
Transmits electrical power into coil which is at rest to make it move, E.M.F alternates
Carbon Brushes
Makes constant contact between coil and circuit to avoid wires becoming twisted.
What is alternating current
Current flow created by electrons continuously changing directions.
(A.C) What happens when coil turns in one direction
Pointer deflected one way, then, the other one.
Because coil cuts through MF lines and a E.M.F is induced in coil
What happens when current flows through a wire
A MF is produced around the wire
Produces lines that are circular around it
As distances increases circules get further apart
MF around solenoid
Similiar to bar magnet, strong and uniform
Clockwise - south
What is a electromagnet?
Soft iron + coil
When is there magnetic field in electromagnets
Current flowing there will be MF
no current flowing, no MF
Factors affecting MF strength around a solenoid
- increasing size of current
- ## increase number of coils
Factors affecting electromagnet
- increase current
Relay
Electromagnets are used in relay circuits
Loudspeakers use oscillation to generate vibrations for sound
Faradays Law
Wire close to changing MF will experience a induced EMF
Experiment for electromagnetic induction
Move bar through a wire coil, see oscillations in galvanometer, see current
Factors affecting force increase
- increase MF
- increase current
- increase wires
- increase turns
- increase length
Factors affecting turning force of a motor
- increase current
- increase number of turns
Split Rings
Once coil has rotated 180, current continues to flow in clockwise. Split ring makes sure direction of current stays the same só force also
What is magnetic effect of a current
- created when current flows through a wire
- needle of compass points in direction of MF
What will happen once a current carrying conductor is places in a MF
Will experience a force if wire is perpendicular because MF exerts a force on each individual elecrrom
Deflect
When a charged particle passes through MF, field exerts force on particle, deflects.
Force is always at 90
Use left hand rule.
Operation of D.C motor
When current is flowing at 90.
Current creates a MF around coil
Force exerted into coil
Current will flow into opposite direction on each side of coil
Force produced from MF will push one side of coil up and other side down
Cause coil to rotate
Vertical position