AC theoryQuestion 906 of 1506

An oscilloscope shows that one cycle of a sine wave takes 4 ms. What is its frequency?

  1. 4 Hz
  2. 25 Hz
  3. 250 Hz
  4. 400 Hz
Show answer

Correct answer: 250 Hz

Frequency is the reciprocal of period: 1 / 0.004 s = 250 Hz.

Source: Lessons in Electric Circuits II: AC (Kuphaldt), 1.2: AC Waveforms

Practice ac theory

Questions last reviewed: 18 October 2026