Key ideas1 of 3
Count complete waves per second
The frequency, f, is the number of complete waves passing a point each second. Its unit is hertz, Hz. A frequency of 4 Hz means four complete waves per second. If 12 complete waves pass a fixed point in 3 seconds, f = 12 ÷ 3 = 4 Hz. Keep the observation point fixed. Timing several cycles reduces the relative effect of a small timing error.
