Notes

Outline

Celtic Harp   Irish folk tunes arranged by Howard Baer

Propagation of Waves Key Terms Reflection Refraction Absorption

Slide 3

Diffraction   Diffraction is significant only when  D £ l

Interference Interference occurs whenever two waves occupy the same space at the same time.

Resultant Wave The combined wave formed by the super-position of two indi-vidual waves

Constructive Interference The two interfering waves reinforce one another Occurs when the two waves are in phase

Constructive Interference

Destructive Interference

Destructive Interference The two interfering waves cancel one another Occurs when the two waves are out of phase

Video I-3   Interference: Transverse Waves on a String.

Constructive Interference – Waves

Destructive Interference – Waves

Constructive Interference (unequal amplitudes)

Destructive Interference (unequal amplitudes)

Sound From Two Sources

Sound From Two Sources Constructive interference occurs when L1 - L2 = n l

Sound From Two Sources Destructive interference occurs when L1 - L2 = (n+ ½)l

Video II-5   Interference of Sound Waves

Beats Occur when two waves of slightly different frequency interfere

Beats

Video II-6 Beats

Beat Frequency fbeat = |f1 -f2|