The word "frequencies" is correct and usable in written English.
You can use it to refer to the rate at which something occurs. For example, "The survey revealed various frequencies of reported allergies."
Sine waves turn up all over the place; more complex waveforms can always be broken down into a series of superimposed sine waves of various frequencies, in a process known as a Fourier transform.
"Binaural beats are particular frequencies that can be played through earphones to stimulate a particular brain state, such as studying or sleeping," he says.
Charismatic politicians and CEOs are good examples, with the ability to consciously or subconsciously push their voices through a wide range of frequencies when addressing the general public to project an image of power and dominance.
The FCC's intention was to prevent interference from one station affecting others broadcasting on adjacent frequencies.
Finally, high-voltage DC provides a handy means for synchronising AC systems that operate on different frequencies.
In other cases the clearest picture emerges by combining images from several frequencies.
It also requires radio broadcasters to transmit their digital signals over an entirely separate swathe of frequencies to their analogue signals.In America, that part of the spectrum is simply not available, having long since been allocated to the armed forces.
Those used for academic work principally rely on amateur-radio frequencies, with basic equipment squeezed into the CubeSat form.
Alternatively, as in the case of forensic evidence when the user does not know precisely what to expect, different combinations of frequencies can be examined to see if anything interesting emerges.
Companies tend to use licensed frequencies and plump for more expensive radio gear to handle their data flows.
Since molecules and dimers absorb different frequencies of light, studying the spectrum of starlight that has passed through a planetary atmosphere could reveal its atmospheric pressure.
