Electromagnetic induction is the induction of emf in a circuit by varying the magnetic flyx linked with the circuit. Emf is induced due to change in flux of a magnetic field.
Field linkage is the product of magnetic flux and the number of turns on the coil N. Lenz's Law states that the direction of induced current is always such that it opposes the flux change that caused it. Faraday's LAw states that the induced emf in a circuit is equal to the rate of change of flux linkage through the circuit. This can be represented as e.m.f = d(Flux Linkage)/dt.
When a coil rotates uniformly in a magnetic field, the coil cuts the flux and an alternating emf is induced.
The root mean square value of an alternating current is the value of direct current that would give the same heating effect as the alternating current in the same resistor.
Oscilloscopes plot the voltage of a circuit over time. An AC source would give a sinusoidal waveform whereas a DC source would give a horizontal line. The Y-gain and the time base can be adjusted to scale the output.
Transformers changes an alternating pd to a different peak value. Low-resistance windings, a laminated core and a core of soft iron increases transformers efficiency.