In the SI system, the frequency of a wave is measured in which unit?

• A. Hertz (Hz), equivalent to $s^{-1}$
• B. Newton (N), equivalent to $kg\cdot m\cdot s^{-2}$
• C. Joule (J), equivalent to $kg\cdot m^2\cdot s^{-2}$
• D. Meter (m)

Answer: (A)

Verified step by step guidance

1. Understand that frequency is defined as the number of oscillations or cycles per unit time.
2. Recall that the SI unit of time is the second (s), so frequency must be expressed in terms of inverse seconds.
3. The unit for frequency is called Hertz (Hz), which is equivalent to one cycle per second.
4. Express this relationship mathematically as \(\text{Hz} = \text{s}^{-1}\), meaning Hertz is the reciprocal of seconds.
5. Compare this with other units: Newton (N) is \(\text{kg} \cdot \text{m} \cdot \text{s}^{-2}\), Joule (J) is \(\text{kg} \cdot \text{m}^2 \cdot \text{s}^{-2}\), and meter (m) is a unit of length, so they do not represent frequency.