# The Naked Scientists Forum

### Author Topic: How does wave change?  (Read 2060 times)

#### jartza

• Sr. Member
• Posts: 230
##### How does wave change?
« on: 21/11/2010 08:23:14 »
We have a standing sound wave in the air inside a closed pipe. We heat the pipe with a torch. Frequency of wave increases. Is this correct?

We have short pulse of sound wave in the air inside a closed pipe. We heat the pipe with a torch. Frequency of wave stays the same. Is this correct?

#### Geezer

• Neilep Level Member
• Posts: 8328
• "Vive la résistance!"
##### How does wave change?
« Reply #1 on: 21/11/2010 08:44:39 »
Sounds like a trick question.

Would you like to learn something, or prove a point?

#### jartza

• Sr. Member
• Posts: 230
##### How does wave change?
« Reply #2 on: 21/11/2010 11:07:01 »
I have a hunch that if you think hard this odd difference of waves, then maybe you will understand something. (here "you" means "anybody")

#### Bill S

• Neilep Level Member
• Posts: 1802
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##### How does wave change?
« Reply #3 on: 21/11/2010 13:27:03 »
Quote
We have short pulse of sound wave in the air inside a closed pipe. We heat the pipe with a torch. Frequency of wave stays the same. Is this correct?

Does the short pulse stay around long enough to be influenced by the temperature change?

#### jartza

• Sr. Member
• Posts: 230
##### How does wave change?
« Reply #4 on: 21/11/2010 16:55:37 »

Does the short pulse stay around long enough to be influenced by the temperature change?

Yes it does.

« Last Edit: 21/11/2010 17:00:27 by jartza »

#### Bill S

• Neilep Level Member
• Posts: 1802
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##### How does wave change?
« Reply #5 on: 21/11/2010 17:35:15 »
Quote
Yes it does.

#### jartza

• Sr. Member
• Posts: 230
##### How does wave change?
« Reply #6 on: 21/11/2010 18:05:13 »

Well, I got confused. There is actually frequency increase in both cases, right?

#### Soul Surfer

• Neilep Level Member
• Posts: 3345
• keep banging the rocks together
##### How does wave change?
« Reply #7 on: 21/11/2010 20:57:53 »
the equivalent of a frequency change in a narrowband (sinusoidal) system is a change of time delay in an impulse system  (assuming that the frequency response is uniform).   However under special circumstances this delay may be frequency sensitive so the single narrowband impulse turns into a "chirp"  a rising or falling sequence of frequencies.

#### The Naked Scientists Forum

##### How does wave change?
« Reply #7 on: 21/11/2010 20:57:53 »