Electromagnetic Induction U4 Flashcards
What is faradays law
The induced emf is directly proportional to the rate of change of flux linkage
What is lenzs law
The induced emf will produce a force that opposes the motion of the conductor i.e a resistance
Define magnetic flux density
The number of magnetic flux lines per metre^2
What is the induced v proportional to
The rate of change of magnetic flux
Define one coulomb
It is the charge transported by one amp in one second
Define an electric field
A region where any charged particle experiences a force
What conditions are required for emf not to be induced and why
The wire needs to be parallel to the magnetic flux lines therefore no lines are crossed so no emf is induced
How do you increase emf
Increase the turns in the coil
Higher B field
Larger A
Increased frequency of coil turns
What does a moving magnet induce
Current
When a moving magnet induces current. What happens to there directions
The current creates it’s own magnetic field
These two magnetic fields (the magnet and wire) interact and act in opposite directions due to lenz’s law
If more flux lines are cut per second what is greater
And what does this cause in turn
Voltage
A current to flow
How do you charge a toothbrush
There is a coil with a metal core inside, current produces a magnetic field which penetrates the plastic casing of the toothbrush and changes magnetic flux/B therefore v is induced in the coil.
One coil has an a.c. To cut the magnetic flux lines inducing a voltage and consequently charging the battery inside
F=
BIL
BQV
Q1Q2/r^2 x k
V=
-dNBA/dt
B=
Magnetic flux/A
