AC Fundamentals Practice Test

AC (alternating current) is the type of power delivered to almost every home and business in the United States, standardized at 60 Hz and 120/240 volts. Unlike DC, AC current reverses direction many times per second, tracing out a sine wave. Know the difference between peak value (the highest point of the wave) and RMS value (the "effective" value that behaves like an equivalent DC voltage for heating purposes) — when someone says "120 volts," they mean RMS. Also get comfortable with frequency (cycles per second, in Hz) and phase (timing between two waveforms).