D4 - Induction Flashcards
what does the magnetic field around a solenoid look like?
draw lines through a coil of wire going in one direction, with arrows indicating this. Draw a loop above and below the coil of wire from one end to the other, with arrows indicating the direction of current
what is the magnetic flux formula for a field and a loop of wire at 90° and at an angle of theta
At 90°: phi = BA
At theta: phi = BAcostheta
What is the flux linkage for a coil of wires with N turns?
N x phi
What is flux linkage
Magnetic flux linkage is the product of the magnetic flux and the number of turns on a coil through which the field passes.
What is Faraday law
The magnitude of induced EMF is directly proportional to the rate of change of magnetic flux
What is lenz’s law
Any current produced by an induced EMF opposes the change which caused it
What is Fleming’s right hand rule
It is used to work out the direction of the induced EMF. The thumb represents motion, the index finger represents field, the middle finger represents induced EMF
What is the equation to find an induced EMF
EMF = -N x dphi/dt
d = differentiation
or change in phi/ change in time
What could you do to make an AC generator into a DC generator
An AC generator can be converted into a DC generator by using half split slit rings, i.e. by cutting those rings in half, and connecting the two ends of the coil to them
What does the graph for voltage against time for the output of an AC and a DC generator look like
- an AC generator on a graph would look like a sign wave going into the positive and the negative values as the current is alternating
– a DC generator would look like a sign wave to, but the curves in the negative side of the graph would be reflected in the X axis so you would have bouncing curves only above the axis. It may look like a bunny hopping
