Magnetic Fields Flashcards
Which way do magnetic field lines point?
From North to South
What is the magnetic flux density?
The force on one meter of wire carrying a current of one amp at right angles to the magnetic field.
What is 1 tesla?
The flux density that produces a force of 1N in a wire of length 1m with 1A at right angles to the magnetic field
Flemings left hand rule
FBI
What shape path do charged particles flow when they enter at right angles to a magnetic field?
Circular as force is always directed towards the center of rotation
What is faradays law?
The induced EMF is directly proportional to the rate of change of flux linkage.
What is Lenz’s law?
The induced EMF is in such a direction as to oppose the change that caused it.
What does the gradient of a flux linkage against time graph represent?
Induced EMF
What does Vrms represent?
.The root mean square of the peak voltage
. Which tells you the equivalent dc voltage to deliver the same amount of power.
What causes inefficiencies in a transformer and how can this be improved?
Flux leakage - fix by using iron core
Eddy currents - fix by using a laminated core.
Resistance in the wires - use thick copper wires
Heating of the wires - use ventilation to cool wires
Which equation can calc the peak power transferred?
Ppeak = Vo x Io
Which equation can calc the mean power transferred?
Pmean = Vrms x Irms
