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Kundt\'s method for measuring the speed of sound. In Fig 17-51, a rod R is clamp

ID: 1638375 • Letter: K

Question

Kundt's method for measuring the speed of sound. In Fig 17-51, a rod R is clamped at its center; a disk D at its end projects into a glass tube that has cork filings spread over its interior. A plunger P is provided at the other end of the tube, and the tube is filled with a gas. The rod is made to oscillate longitudinally at frequency f to produce sound waves inside the gas, and the location of the plunger is adjusted until a standing sound wave pattern is set up inside the tube. Once the standing wave is set up, the motion of the gas molecules causes the cork filings to collect in a pattern of ridges at the displacement nodes. If f = 4.46 times 10^3 Hz and the separation between ridges is 9.20 cm, what is the speed of sound in the gas?

Explanation / Answer

Velocity of sound can be calculated using formula =

Wavelength * frequency

Wavelength of sound wave will be twice of length of separation between ridges I.e. 2 * 9.20 = 18.40cm or .1840m

Frequency is 4460Hz

So v = 4460 * .1840 = 820.64m/s