Wave Period

The period of a wave is the time taken for one full cycle, such as one crest-to-crest or vibration-to-vibration repeat. Frequency tells you how many cycles happen each second, so period must be the time for one cycle: if more cycles fit into a second, each one must take less time. That is why period and frequency are reciprocals, giving T = 1/f.

Use this when you know a wave’s frequency and need the time for one oscillation, or when converting between hertz and seconds. It is common in sound, light, pendulums, and any repeating signal or wave motion.

• Using the frequency value directly as the period instead of taking the reciprocal
• Forgetting to convert the answer to seconds when interpreting the result
• Mixing up period and frequency units, such as writing Hz for period or s for frequency