What Hertz Measures
The abbreviation “Hz” in science stands for Hertz, a fundamental unit of measurement within the International System of Units (SI). Hertz quantifies frequency, describing how often a repeating event or phenomenon occurs within a given period, specifically how many cycles happen in one second. This unit provides a standardized way to express the rate of various oscillations and vibrations across many scientific and engineering fields.
Hertz specifically measures the number of cycles per second. A “cycle” refers to one complete repetition of a periodic event. For instance, if something vibrates 10 times in one second, its frequency is 10 Hertz. This unit is named in honor of Heinrich Rudolf Hertz, a German physicist who, in the late 19th century, conclusively demonstrated the existence of electromagnetic waves, laying groundwork for radio and other technologies. His work established the measurable nature of these waves and their periodic behavior.
Where You Encounter Hertz
Hertz is encountered in many aspects of daily life and technology. In acoustics, Hertz describes the pitch of a sound. Human hearing typically ranges from about 20 Hz, representing very low-pitched sounds, up to 20,000 Hz (or 20 kilohertz), which corresponds to high-pitched sounds.
In electrical systems, Hertz indicates the frequency of alternating current (AC). For example, household electrical outlets in North and South America primarily use 60 Hz, meaning the current reverses direction 60 times per second. Conversely, most of Europe, Asia, Africa, and Australia standardize on 50 Hz. This difference stems from historical developments in electrical infrastructure and requires compatible devices or frequency converters for international use.
Hertz also plays a significant role in modern electronics and computing. Monitor refresh rates, measured in Hz, indicate how many times a screen updates its image per second. A 60 Hz monitor refreshes 60 times each second, while a 144 Hz monitor updates 144 times, resulting in smoother motion and a more fluid visual experience, especially noticeable in fast-paced video games.
The speed of a computer’s central processing unit (CPU) is often expressed in gigahertz (GHz), which represents billions of cycles per second. A higher GHz rating generally signifies that the processor can execute more instructions per second, contributing to faster computing performance. Radio waves, including those used for Wi-Fi and broadcast radio stations, are also characterized by their frequencies, typically measured in kilohertz (kHz), megahertz (MHz), or gigahertz (GHz).