Which of the following correctly defines frequency?

Frequency is defined as the number of cycles of a periodic phenomenon that occur in a unit of time, which is typically expressed in hertz (Hz). In this context, the equation that correctly captures this definition is the inverse of the time taken for one complete cycle. Therefore, when you take 1 divided by the time taken for a single cycle, you quantify how many cycles occur in one second, which is precisely what frequency measures.

By understanding this definition, it becomes clear why the other options do not accurately describe frequency. The other choices involve different physical quantities and relationships: energy and charge relate to electrical potential or work done, voltage and charge pertain to electrical energy transformations, and resistance and voltage depict Ohm's law. None of these represent the fundamental concept of how often an event occurs within a specified timeframe, ensuring that the concept of frequency is distinctly articulated by the first choice.