In the SI system, what is the unit of wave frequency?

• A. Watt (W)
• B. Newton (N)
• C. Meter (m)
• D. Hertz (Hz), equivalent to $s^{-1}$

Answer: (D)

Verified step by step guidance

1. Understand that wave frequency refers to how many wave cycles pass a point per unit time.
2. Recall that frequency is defined as the reciprocal of the period, which is the time taken for one complete cycle: \(f = \frac{1}{T}\), where \(f\) is frequency and \(T\) is period.
3. Since the period \(T\) is measured in seconds (s), the unit of frequency is the reciprocal of seconds, or \(s^{-1}\).
4. Recognize that the SI unit for frequency is called the Hertz (Hz), where 1 Hz = 1 \(s^{-1}\).
5. Note that other units given (Watt, Newton, Meter) correspond to power, force, and length respectively, and are not units of frequency.