周期

1. Origins, structure, and basic meaning

• Structure: 周期 is read as しゅうき and is a noun for a cycle or the period required for the same state or event to recur.
• Basic usage: Use 往復する周期を測る for measuring one interval and 一定の周期で葉を出す for regular recurrence.

2. Common pitfalls and similar expressions

• Period versus frequency
  • A period is the interval for one repetition, while frequency counts repetitions per unit of time.
• A complete return cycle
  • For the pendulum, 往復 makes the full trip out and back the unit being timed.