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When to use $f$ and when $\nu$ signifying frequency? I guess that when you mean frequency of electromagnetic wave, you use $\nu$, and $f$ otherwise?

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up vote 4 down vote accepted

Those notations are equivalent and are interchangeably used for the same quantity. Still, $f$ is more commonly used in engineering sciences, while $\nu$ is preferred by physicists.

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Just a note: there are also local specifics, in some languages one or the other notation is more preferred... – Pygmalion Apr 16 '12 at 19:25
Could you provide any example of such localisation? It sounds rather interesting. I always assumed what your answer states, that we physicists prefer $\nu$. – Alfredo Hernández Nov 19 '14 at 8:10
@AlfredoHernández I have few books on physics in Slovenian, and they usually use $f$. – Pygmalion Nov 22 '14 at 11:28

In any work, you should pick a convention and stick to it.

In my own work, I typically use $f$ for audio frequencies and $\nu$ for optical frequencies, both in Hz. I use $\omega$ for the angular frequency $\omega = 2\pi f$.

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I use the same convention. I think $\nu$ is preferred for only optical. $f$ is generally used for audio and oscillatory(AC circuits, pendulums, etc) frequencies. But there's no hard-and-fast rule. – Manishearth Apr 17 '12 at 7:27
If you have a textbook that covers all areas, optical as well as oscillatory, usualy one convention is used. E.g. Serway consistently use $f$, perhaps because it is a book intended for engineers. Too bad there is no notation convention, comparable to SI units. – Pygmalion Apr 17 '12 at 7:42

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