PHYSICS 109 Lecture Notes - Lecture 3: Tuning Fork, Sound, Lightning
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Physics 109 - lecture 3 - superposition and beats, harmony, waves (9/14/16) Superposition - when more than one oscillation is present. The principle of superposition states that pressure disturbances from multiple sources add. Two waves with same frequency with no degree change will add up a+b. Two waves with same frequency but a 90 degree change will add up but will be less than a+b. Two waves with the same frequency but a 180 degree change will cancel each other out: a-b. Add two waves: p1(t) = a sin(360o * f t) and p2(t) = b sin(360o * f t - ) The amplitude of the sum of the waves ( p1(t) + p2(t) ) depends on the , also known as the phase difference between p1 and p2. When = 0 the amplitude is p1+p2. When = 180o () the amplitude is p1 - p2.