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Unformatted text preview: Lecture 22 Purdue University, Physics 220 1 Lecture 22 Sound Textbook Chapter 12.112.8 PHYSICS 220 Lecture 22 Purdue University, Physics 220 2 Overview • Last Lecture – Interference and Diffraction • Constructive, destructive • Diffraction: bending of waves around obstacles – Coherence • Same frequency and constant phase difference – Reflection and Refraction • fixed point inverts wave • sin θ 1 /sin θ 2 = v 1 /v 2 – Standing Waves (fixed ends) • λ n = 2L/n • f n = n v / 2L • Today Lecture 22 Purdue University, Physics 220 2 Overview • Last Lecture – Interference and Diffraction • Constructive, destructive • Diffraction: bending of waves around obstacles – Coherence • Same frequency and constant phase difference – Reflection and Refraction • fixed point inverts wave • sin θ 1 /sin θ 2 = v 1 /v 2 – Standing Waves (fixed ends) • λ n = 2L/n • f n = n v / 2L • Today – Sound Waves Lecture 22 Purdue University, Physics 220 3 Sound Waves Lecture 22 Purdue University, Physics 220 4 Speed of Sound • Recall for pulse on string: v = sqrt(F / μ ) • For fluids: v = sqrt(B/ ρ ) – B = bulk modulus: • For ideal gas: the speed of sound is proportional to the square root of the absolute temperature, but independent of pressure and density 5600 Steel 1500 Water 972 Helium 343 Air Speed (m/s) Medium T in Kelvin T = 0 C or 273 K Lecture 22 Purdue University, Physics 220 5 Intensity and Pitch • For Sound Waves...
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This note was uploaded on 09/17/2010 for the course PHYS 220 taught by Professor Chang during the Spring '09 term at Purdue.
 Spring '09
 CHANG

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