Electronics - Alternating Current vs Direct Current

DC current flows in one direction, while ac current rises from zero to a maximum, then falls to zero in one direction, then rises to a maximum, then falls to zero in the opposite direction.

A square and a rectangular waveform appear to have a step voltage transition.

The duty cycle of a square wave with a pulse width of 3 s and a period of 9 s is 40%.

The rms value of a sine wave is .707 x peak-to-peak value/2.

DC current transfers better over longer distances than ac current.