| Different frequencies, measured in hertz, or cycles per second, indicate different levels and types of activities. |
| We see frequencies of hundreds of hertz, or hundreds of revolutions of the disk per second. |
| At random times the program changed the dot's frequency up or down by up to a few tenths of a hertz. |
| The sounds and charges transmit in the low frequency range of 20 hertz, which is barely audible to the human ear. |
| A gravity wave with a frequency of 1,000 hertz, for example, spans nearly 200 miles from peak to peak. |
| Most pneumatic isolators operate effectively above several hertz, but at their natural frequency they actually provide some amplification. |
