Is That The Phone?

Honors Physics students regaled each other with the dulcet tones of a touch-tone phone symphony in lab today. Add tuning forks and vocalized vowels and you have a solid lesson on tones and overtones. The tuning forks gave nice pure tones when struck on a soft surface and a good sprinkling of overtones when struck on a hard surface. Whether the overtones were harmonic or inharmonic would need to be determined by a bit of math (that we will cover tomorrow), but it was easy to document their existence and their frequencies. Folks also got to investigate how a touch-tone phone uses sound to code numbers. Phone companies use the row frequency and column frequency combination to recognize what numbers are being dialed. Students were quickly able to discern the pattern and corroborated that the final row, consisting of *, 0 and # followed the same pattern.

Physics discussed the Doppler Effect on both sound and light waves. Intensity, as an inverse-square relationship was examined, as were the various scales used to report sound intensity. Relative intensity and the decibel scale was given special attention, as was the effect of various sound intensities on the human ear. We started discussing forced vibrations today and, after tomorrow's lab, will extend the discussion to the concept of resonance and harmonics.

Physical Science explored the electromagnetic spectrum. Remember that all EM waves travel the same speed in a vacuum (3 x 10⁸ m/s), regardless of frequency. Waves with higher frequencies carry more energy (think back on the particle model of light) and waves with lower frequencies are less energetic. We'll explore how this frequency/energy difference affects various behaviors of light as we move through this unit. Tomorrow, we'll focus our attention on reflection and that will be the topic of Thursday's lab.