# Fundamental Frequency

Which of the following could be the fundamental freq. for a vibration that has an overtone freq. of 990 Hz?

a. 330
b. 660
c. 148
d. 1980
e. 1990
(All in Hz.)

The formula that I think you have to use is f_n = n*f_1, where f_1 is fud. freq.

Then, I thought

f_2 = 2*f_1, where f_2 is the overtone freq. (is these a correct assumption?)

but 990/2 is 495.

Could someone direct me to the correct path of getting the solution?

I'm confused over the definitions of overtone and fund. freq.

Thanks.

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Gokul43201
Staff Emeritus
Gold Member
There's no reason to assume than n=2, so you just leave it as n.

So you have $f_n = nf_1$
Or $f_1 = \frac {990}{n}$

Which of the choices satisfies this condition for some integer n ?

Can you say if $f_1$ will be greater than or less than 990 Hz, from this ? Does this rule out any choices ?

The alternative is simply to notice that $f_n/f_1 = n$, so try the remaining choices of $f_1$ to see which one gives you an integer ratio.

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