Lecture 20

# Lecture 20 - PHYSICS 220 Lecture 20 Waves Lecture 20 Purdue...

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PHYSICS 220 Lecture 20 Waves Lecture 20 Purdue University, Physics 220 1

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Superposition Principle • When two or more waves pass through the same region the actual displacement is the sum of the separate displacements. • If two waves pass through the same region they continue to move independently. Lecture 19 Purdue University, Physics 220 2 y ( x , t ) = y 1 ( x , t ) + y 2 ( x , t )
Energy (intensity) of a wave The intensity of a wave is proportional to the square of the amplitude Lecture 19 Purdue University, Physics 220 3 I A 2 For a spring U = 1 2 kx 2 x for a spring is like A for a wave

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Constructive Interference Lecture 20 Purdue University, Physics 220 4 The net disturbance is the sum of the individual disturbances. When waves cross in a point and have the same sign amplitude, they add constructively. Since intensity is proportional to amplitude squared, the resulted intensity is more than the sum of the intensities of individual waves.
Destructive Interference Lecture 20 Purdue University, Physics 220 5 The net disturbance is the sum of the individual disturbances. When waves cross in a point and have the opposite sign amplitude, they add destructively. Since intensity is proportional to amplitude squared, the resulted intensity is less than the sum of the intensities of individual waves.

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Interference Lecture 20 Purdue University, Physics 220 6 Constructive Destructive
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## This note was uploaded on 05/03/2011 for the course PHYS 220 taught by Professor Chang during the Spring '09 term at Purdue.

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Lecture 20 - PHYSICS 220 Lecture 20 Waves Lecture 20 Purdue...

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