About Frequency Units
Frequency measures the number of occurrences of a repeating event per unit of time. The SI unit is the Hertz (Hz), defined as one cycle per second. For practical use, various prefixed units are employed: kilohertz (kHz) for audio frequencies, megahertz (MHz) for radio, gigahertz (GHz) for microwave and computing, and terahertz (THz) for far-infrared radiation.
RPM (revolutions per minute) is commonly used in mechanical engineering for rotating machinery. One RPM equals 1/60 Hz. Angular frequency in radians per second is preferred in physics and electrical engineering, where omega = 2 pi f.
Conversion Formulas
Conversion Reference Table
| Value | Hz | kHz | MHz | GHz |
|---|---|---|---|---|
| 1 Hz | 1 | 0.001 | 0.000001 | 10-9 |
| 1 kHz | 1,000 | 1 | 0.001 | 10-6 |
| 1 MHz | 106 | 1,000 | 1 | 0.001 |
| 1 GHz | 109 | 106 | 1,000 | 1 |
Frequently Asked Questions
How do I convert MHz to GHz?
Divide by 1000. For example, 2400 MHz = 2.4 GHz. This is commonly needed when working with Wi-Fi specifications, which may be listed in either unit.
What is the relationship between RPM and Hz?
RPM divided by 60 gives Hz. A motor spinning at 3600 RPM completes 3600/60 = 60 revolutions per second, or 60 Hz. This matches the US power grid frequency, which is why many synchronous motors run at 3600 RPM.
When should I use angular frequency instead of regular frequency?
Angular frequency (radians per second) is used extensively in physics equations involving sinusoidal functions, resonance calculations, and complex impedance in AC circuits. It simplifies many mathematical expressions by eliminating factors of 2 pi.