Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Destructive Interference, Cosine Wave
Name: N/A
Status: N/A
Age: N/A
Location: N/A
Country: N/A
Date: N/A


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.



Click here to return to the Physics Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (help@newton.dep.anl.gov), or at Argonne's Educational Programs

NEWTON AND ASK A SCIENTIST
Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory