Constructive interference:
loud (reinforcement) if waves arrive in step:
|d1-d2| = nl (n = whole number, 0,1, 2, 3Ö.)
+ - + - + - + - + - + - + - + - + - + -
+ - + - + - + - + - + - + - + - + - + -
d1
d2
Destructive interference:
no sound if waves arrive 180O out of step:
|d1-d2| = (n+1/2)l (n = whole number)
oh, no sound!
destructive
interference!
demo; example (homework)
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