What is a measure of how many cycles occur in one second?

The correct answer is Hertz, which is the standard unit of frequency in the International System of Units (SI). It quantifies the number of cycles of a periodic phenomenon that occur in one second. For instance, if a signal oscillates 60 times in one second, it is said to have a frequency of 60 Hertz.

This measurement is vital in various fields, such as telecommunications, where it helps in determining the frequency of signals, ensuring proper transmission, and avoiding interference between different channels. Understanding Hertz is crucial for technicians who work with electrical systems, as it directly relates to how systems behave and interact at different frequencies.

The other units listed serve different purposes and do not measure frequency. Watts measure power, which is the rate at which energy is used or produced. Decibels are used to express the intensity of sound or power levels in a logarithmic scale, often in relation to a reference level. Bels, while similar to decibels, are a less common unit for expressing logarithmic ratios, particularly in sound and power levels, but they do not measure frequency either. Understanding these distinctions highlights the importance of Hertz as the relevant measurement for cycles per second.