Physics 312 Lecture: "Superposition of Waves and Standing Waves I." Apr 10, 1998

• When two sinusoidal waves with identical frequencies and wavelengths interfere, the result is another wave with the same frequency and wavelength, but a maximum amplitude which depends on the phase difference between the input waves.
• Constructive interference occurs when the phase difference between two waves is zero, or some multiple of pi radians
• Destructive interference occurs when the phase difference between two waves is some multiple of pi/2 radians
• Adding two sound waves which are out of phase may yield silence!
• Standing waves occur when a wave reflects back and forth in a confined space and interferes with itself
• Nodes are locations where a standing wave has zero amplitude
• Antinodes are locations where a standing wave has maximum amplitude
• Waves travelling on a string fixed at both ends are constrained to have specific wavelengths and frequencies

This lecture discusses material in Chapter 18 of Serway.

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