- #1

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## Homework Statement

The resonant length of a closed air column at the first resonance is 0.375m, what is the wavelength when at 4th reasonance

## Homework Equations

## The Attempt at a Solution

1/4λ=0.375m

λ=1.5m

1.5m/7 = 0.214m

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- Thread starter hamza2095
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- #1

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The resonant length of a closed air column at the first resonance is 0.375m, what is the wavelength when at 4th reasonance

1/4λ=0.375m

λ=1.5m

1.5m/7 = 0.214m

- #2

Merlin3189

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I agree with your wavelength at first resonance and your answer.

- #3

TSny

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As third poster, I second your fourth resonance answer.

- #4

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This was a question on a test, the way I got the answer was knowing v/f=λ and i knew that 7/4 of the wave fits in the 4th reasonance and 1/4 in the first, meaning the frequency is 7x more. I assumed the the velocity was 1.5m/s and the frequency was 1hz so 1.5ms/1hz = 1.5m, after that i mutliplied the 1 hz by 7 to get the answer. Is there an easier way to go about this?, I had trouble with it because the neither the speed of sound or frequency was given.As third poster, I second your fourth resonance answer.

- #5

TSny

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That's the key.i knew that 7/4 of the wave fits in the 4th reasonance

Note that the 0.375 m given in the problem represents the length of the pipe. So 7/4 λ = 0.375 m.

You don't need to assume a value for f.

- #6

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Ohhh okay I see, thank you. I knew there was an easier way to look at it.

- #7

TSny

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Good. Drawing pictures for these types of problems is always a good thing to do.

- #8

Merlin3189

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You may notice my first post is oddly worded, because you tricked me into thinking you'd done the second part wrongly and I had to edit it!

I had ##\frac{λ_1}{4}=0.375## and ##\frac{7λ_2}{4}=0.375## so when I saw your /7 I thought at first you'd missed out the 4.

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