PURPOSE: Demonstrate addition of two sine waves with variable phase difference.

DESCRIPTION: Two identical sine waves from the University of Maryland Fourier Synthesizer are added together and the sum is viewed along with each component using a three-trace oscilloscope. The sum can be studied as the phases of one or both of the component waves are varied.

This demonstration can be used as an aid in the study of beats or interference of sound waves.

SUGGESTIONS:

See Question of the Week #213 for information on using this demonstration to enhance class involvement.

REFERENCES: (PIRA unknown.)

EQUIPMENT: Fourier synthesizer with triple-trace oscilloscope.

SETUP TIME: 5 min.