radio frequency

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frequency

 [fre´kwen-se]
1. the number of occurrences of a periodic or recurrent process in a unit of time, such as the number of electrical cycles per second measured in hertz. In cardiac pacing terminology, frequency is expressed by the formula: frequency = ½ × pulse width.
2. the number of occurrences of a particular event or the number of members of a population or statistical sample falling in a particular class.
radio frequency the range of frequencies of electromagnetic radiation between 10 kilohertz and 100 gigahertz, used for radio communication.
relative frequency the ratio of the number of occurrences of a specified phenomenon in a population to the total size of the population.
urinary frequency urination at short intervals without increase in daily volume of urinary output, due to reduced bladder capacity or cystitis.

radio frequency

An MRI term for an electromagnetic wave with a frequency in the same range as that used for transmitting radio and television signals. The RF pulses used in MRI are usually in the 1–100 megahertz range, which cause heating of a structure or tissue due to RF pulse absorption.