Question

1. what is frequency measured in?

hertz
joules
kilowatt hours
period

Explanation:

Frequency is a measure of how often something occurs. In physics, the standard unit for frequency is hertz (Hz). Joules are the unit for energy. Kilowatt - hours are a unit of energy consumption (especially for electrical energy). Period is the time taken for one complete cycle, and it is the reciprocal of frequency ($T=\frac{1}{f}$ where $T$ is period and $f$ is frequency), but it is not a unit of frequency.

Answer:

hertz