Lectures on Physics has been derived from Benjamin Crowell's Light and Matter series of free introductory textbooks on physics. See the editorial for more information....

Frequency of a radio station

Question: KLON's frequency is 88.1 MHz. What does this mean, and what period does this correspond to?

Solution: The metric prefix M- is mega-, i.e. millions. The radio waves emitted by KLON's transmitting antenna vibrate 88.1 million times per second. This corresponds to a period of

T = 1/f = 1.14x10 -8 s .

This example shows a second reason why we normally speak in terms of frequency rather than period: it would be painful to have to refer to such small time intervals routinely. I could abbreviate by telling people that KLON's period was 11.4 nanoseconds, but most people are more familiar with the big metric prefixes than with the small ones.

Last Update: 2009-06-21