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In 1899 Austrian chemist von Zaynek determined the rate of heat production in tissue as a function of frequency and current density, and first proposed using high-frequency currents for deep heating therapy. [7] In 1908 German physician Karl Franz Nagelschmidt coined the term diathermy, and performed the first extensive experiments on patients. [8]
A440 (also known as Stuttgart pitch [1]) is the musical pitch corresponding to an audio frequency of 440 Hz, which serves as a tuning standard for the musical note of A above middle C, or A 4 in scientific pitch notation.
In such cases, excitatory input voltages are applied in different modes, by a stimulation rate of 0.1 to 100 Hz, current stimulation amplitudes of 0 to 200 mA and load resistance of 1 kΩ, which gives 0-200 mV amplitude (in case of constant resistance) and 40 mW electrical power. [8]
A jump from the lowest semitone to the highest semitone in one octave doubles the frequency (for example, the fifth A is 440 Hz and the sixth A is 880 Hz). The frequency of a pitch is derived by multiplying (ascending) or dividing (descending) the frequency of the previous pitch by the twelfth root of two (approximately 1.059463).
Extremely low frequency EM waves can span from 0 Hz to 3 kHz, though definitions vary across disciplines. The maximum recommended exposure for the general public is 5 kV/m. [20] ELF waves around 50 Hz to 60 Hz are emitted by power generators, transmission lines and distribution lines, power cables, and electric appliances. Typical household ...
A440 Play ⓘ. 440 Hz = 4.21 or 4.39. The Bark scale is a psychoacoustical scale proposed by Eberhard Zwicker in 1961. It is named after Heinrich Barkhausen, who proposed the first subjective measurements of loudness. [1] One definition of the term is "a frequency scale on which equal distances correspond with perceptually equal distances.
The electromagnetic spectrum is the full range of electromagnetic radiation, organized by frequency or wavelength. The spectrum is divided into separate bands, with different names for the electromagnetic waves within each band. From low to high frequency these are: radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and ...
1 hertz (Hz) 1 to 1.66 Hz: Approximate frequency of an adult human's resting heart beat: 1 Hz: 60 bpm, common tempo in music 2 Hz: 120 bpm, common tempo in music ~7.83 Hz: Fundamental frequency of the Schumann resonances: 10 1: 10 hertz 10 Hz: Cyclic rate of a typical automobile engine at idle (equivalent to 600 rpm) 12 Hz