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Sound Interference
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I'm having a hard time with this problem. A lecturer is demonstrating a two-slit interference with sound waves. Two speakers are used 1.1 m apart. The sound frequency is 1140 Hz and the speed of sound is 343 m/s. Students sit facing the speakers in a row of seats 6.1 m away. Along the row of students, what is the spacing between the locations on either side of the center line where no sound is heard due to destructive interference? The angle is too large to use angel approximation. Answer in m. Okay, I've gotten as far as computing the angle, but I don't know what to use for "m" in the formula. I've tried 1/2, but that's wrong, so do I use 1.5? (You use halves for minimums right?) |
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Re: Sound Interference
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by SuicidopoliS
on 2009-01-29 08:57:58 (edited 2009-01-29 08:59:53)
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... You do know "m" stands for "meters" in this context, right? And since i guess you do, i also guess i don't have a clue what "formula" you are referring to, so could you perhaps be a tiny bit more specific? This been said, if you computed "the angle" like you say you do, i don't see your problem... I mean, i'm guessing this infamous angle is the angle between the normal to the line between the two speakers, at the center point between the two speakers, and the point on the row of students where there is destructive interference (yeah, i know, it's a long sentence that seems very complicated, but actually really isn't)? So, if you have this angle, it's easy to compute the distance from the center line to this point. Just multiply by 2 (because the question was "the spacing between the locations on EITHER side of the center line), and you have got your answer! Or maybe i got the question all wrong, which is usually a pretty good guess also... .oO° Life's THE CURE, the rest are details! °Oo. |
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Re: Sound Interference
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| Sorry, I means "m" as the number for the maximums. (m=1,2,3...). But, yeah, using your method, I got the answer. I just misunderstood what the question meant. I thought it meant the distance from the central maximum to the first minimum, so I didn't multiply it by 2. Thanks. |