Yes, We're Still on Waves

Intro Physics conducted a lab investigation on sound waves, looking at properties of sound for tuning forks, the human voice, an automated tone dialer and musical instruments.  We contrasted pure tones, with tones accompanied by overtones.  A tuning fork struck softly vibrates with a sole, fundamental frequency, but one that is struck sharply produces overtones simultaneously with the fundamental tone.  The human voice produces a variable number of overtones with the fundamental frequency and that gives each voice its characteristic sound.  The same is true for musical instruments.  Two instruments playing the same note do not sound the same due to the numbers and intensities of overtones produced by each instrument.  For the tone dialer, it was seen that the phone company assigns each number a row and column frequency to indicate its position on the matrix.  We will talk about this lab on Monday and then spend more time with sound intensity.

Physics D, F and Honors Physics started work on wave interference and diffraction today.  We discussed the conditions required to observe interference of light and how those conditions could be and were met to demonstrate light interference as part of the evidence package that light was actually a wave.  Folks saw laser light interference and the dark/light fringes characteristic of light interference and we then looked at how to calculate the position of those fringes.  On Monday, we'll add diffraction to the discussion, which helps to explain how Young's double-slit experiment was able to document light interference.