Can frequency be in micro hertz?

Answer 1

Yes.

The definition of "hertz" is a unit of frequency that occurs once every one second. If something occurs once every second, it does so at a rate of one hertz. If it occurs at a rate greater than once every second, such as ten times per second, then it occurs at a frequency greater than one hertz (10 hertz for this particular example).

Going in the other direction, frequency can also be represented in measurements smaller than one (just as with anything else - milliamps in current being the first example to come to mind). Therefore, if something occurs at a rate slower than once per second, then it occurs at a frequency of less than one hertz. Since the ratio of frequency to time for hertz is 1:1, then it's easy to determine either the rate or the frequency by taking the reciprocal of whichever one you already have. An example would be that if something occurs at a rate of three times every second, then the ratio of frequency to rate would be 3:1, having a frequency of three hertz. If it occurs once every three seconds, then the ratio would be 1:3, meaning the frequency would be 1/3 hertz.

Since one microhertz would be 1/1000000 of 1 hertz (or 1^-6 hertz), something can occur at a frequency of one microhertz if it only occurs once every 1000000 seconds. For a more easier understanding, that's roughly once every ~11.574 days. Or to make it more fun, you age at a rate of 1:(365.242199*24*60*60), which is at a frequency of ~31.557 microhertz.

Probably drew out the explanation more than you needed, but hopefully it answered your question completely.