What you will learn in Alternating Current

1. 1. 230 Volts Is Not the Peak

   A quantity whose average is exactly zero can boil a kettle. What a meter reads is the root of the mean of the square, and this is where that comes from.

2. 2. Opposition That Depends on Frequency

   A capacitor blocks a battery and passes a radio signal. An inductor does the opposite. Neither behaviour is a resistance.

3. 3. Why the Voltages Do Not Add Up

   Measure across each component of a series circuit, add the readings, and you will not get the supply voltage. The meter is fine.

4. 4. Where the Two Oppositions Cancel

   One frequency at which the reactances are equal and opposite — and every consequence a textbook lists is that one cancellation restated.

5. 5. Power That Flows Backwards

   A reactive load returns energy to the supply for part of every cycle, and at a quarter cycle of phase it returns all of it.

6. 6. Why the Wall Socket Alternates

   A transformer trades voltage for current at constant power, works only on a changing flux, and settled an argument in 1890.