Re: standing waves

["John S. Denker" <jsd@MONMOUTH.COM>]

Savinainen Antti wrote:
> I have undestood that standing waves
> (fundamental and higher harmonics) are produces on any object that is set onto
> vibration.

Certainly "can be" produced.  The extent to which they "are" produced
depends on the excitation.

> Then I read from a high school physics book that a tuning fork would
> have only one frequency and no higher harmonics at all.

Hogwash.

> Well, I checked one tuning fork using a microscope and oscilloscope. The signal
> was quite sinusoidal but it was altered significantly. To me it looked like an
> interference between the fundamental frequency and harmonics. Performing a
> Fourier analysis could separate the signal into components but I do not have
> that possibility at school.

Really no possibility?
All you need is a computer with a sound card.

Free software to do the FFT (and hundreds of other good things)
is available from http://www-rocq.inria.fr/scilab/

And for that matter, you don't need technology at all.
You can HEAR the harmonics.  Flick your fingernail against
the tuning fork.  You will hear a bell-like high-pitched
clink.  The higher modes die out more quickly than the
fundamental, so they don't significantly impede the normal
use of the fork.