Section 13-1: Sound Waves

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Section 13-1: Sound Waves -When a tuning fork is hit, the prong swings to the right and the molecules are pressed closer together. compression-the region of high molecular density and air pressure -When the prong moves to the left, the molecules to the right spread apart. rarefaction-area of low air pressure and density -As the tuning fork continues to vibrate, it sends out a series of compressions and rarefactions in all directions like ripples in a pond. -Sound waves are longitudinal. audible sound waves-what humans hear; between 20 and 20,000 Hz infrasonic-less than 20 Hz ultrasonic-higher than 20,000 Hz; used to produce images inside the body because short wavelengths are easily reflected off a small object ex.-Dolphins use short…show more content…
-Medium range frequencies can be heard at lower intensities. Sound at low frequencies (below 50 Hz) and high frequencies (above 12,000 Hz) must relatively intense in order to be heard. -Intensity and distance have an inverse square relationship. formula: P/4πr2 -Frequency determines pitch and intensity (amplitude) determines volume. relative intensity-relates the intensity of a given sound to the intensity at the threshold of hearing (decibel level); a difference in 10 dB means the sound doubles forced vibrations-when vibrations are transferred from one object to another natural frequency-frequency at which something vibrates resonance-when the frequency of a force matches the natural frequency of vibration of a system; sound will transfer at a greater intensity Section 13-3: Harmonics -In a vibrating string, a variety of standing waves can occur (two waves of the same frequency, wavelength, and amplitude travel in opposite directions and

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