Harmonics, Beats and Speed

B Block Alert - Homework is not 13B and 13.2, it is 13B and 13.3 - hopefully, you caught that...

B and C Blocks looked at the concepts of harmonics and how harmonic series are formed by different musical instruments. Stringed instruments and pipes open at both ends can form all harmonics of a fundamental frequency and the standing waveform of the fundamental frequency is a single antinode representing 1/2λ. Pipes closed at one end can only form odd harmonics and their simplest standing wave is 1/4λ. We discussed how harmonics promote musical quality and how they give the individual personalities to specific instruments. We then turned attention to beats, which are produced by interference of sound waves of similar frequencies. We looked at beat formation on the computer using two tuning forks and a microphone and the alternating areas of constructive and destructive interference that typify beat patterns were clearly visible. Tomorrow, we take time to investigate the speed of sound in air and how it is influenced by temperature.

E and F Blocks worked on the Speed of Sound lab, which used echoes in a tube to measure speed of sound using the v = Δx/t equation. The measured values lined up pretty well with the expected values and when the air was heated with a hair dryer, the speed of sound increased accordingly. If the particles are traveling faster, they pass along the energy more quickly so the wave travels faster. We'll discuss the lab tomorrow and E Block will begin their review process. F Block will discuss the concept of beats and beat frequency and look at beat formation on the computer.