Question:
Hi my name is Matt I am doing research right now on resonant frequencies and a little on destructive interference
I am interested in finding some experiments that could help me learn
I've found that the cosine wave is 90 degrees out of phase from a sine
wave, so is a negative sine wave 180 degrees from a regular sine or do
you have to use a different function. What if I want a wave 45 or 30 degrees
out of phase? Most of this I am going to try to directly apply to the electronics field. Also if anyone knows a schematic or plans for a inexpensive home-made sine wave generator I would be glad to hear from you. Any response would be welcome
matthew e greer

Replies:
Yes, a negative sine wave is 180 degrees from a regular sine.
Actually, you can use a sine (or cosine) to describe all the
different phase angles. If the frequency is w then the
sine wave is described by
sin(wt)
If you just add whatever angle you want to the wt angle then you
have what you want:
sin(wt + p)
is the expression for a sine wave shifted by an angle p. You
can check for yourself that sin(wt + 90) = cos(wt), and
sin(wt + 180) = -sin(wt) (that is assuming you are calculated
the angles in degrees).
Oh the "t" in the above expressions is supposed to mean time.

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