Register to reply

Understanding the spectrum of frequencies

by Jacobim
Tags: frequencies, spectrum
Share this thread:
Jacobim
#1
May5-13, 09:21 AM
P: 23
What is the distinction between EM waves and Sound waves.

I know that sound is cyclical vibrations in some sort of medium. When the frequency increases, do these vibrations become EM waves?

I know that EM waves do not need a physical medium. But they are still energy, and sound is energy. So do they belong on the same diagram showing freqencies?

Are sound and EM waves completely seperate things, or are they the same things but at different frequencies?

For instance, the frequency of an AC circuit. 60 hz. Does this produce a 60 hz sound wave in the air from the wire vibrating?

No it does not, be cause the thing that is oscilating is the potential in the conductor.

Is there some crossover point where energy vibrates in the EM spectrum and not in the sound spectrum?
Phys.Org News Partner Physics news on Phys.org
'Squid skin' metamaterials project yields vivid color display
Team finds elusive quantum transformations near absolute zero
Scientists control surface tension to manipulate liquid metals (w/ Video)
Nugatory
#2
May5-13, 09:37 AM
Mentor
P: 3,926
Quote Quote by Jacobim View Post
What is the distinction between EM waves and Sound waves.
They are no more related to one another than they are to ocean waves, or to the swaying of trees in the wind. Many different things can move back and forth for many different reasons, and the only thing they have in common is that they're waving back and forth.

I know that sound is cyclical vibrations in some sort of medium. When the frequency increases, do these vibrations become EM waves?

I know that EM waves do not need a physical medium. But they are still energy, and sound is energy. So do they belong on the same diagram showing freqencies?

Are sound and EM waves completely separate things, or are they the same things but at different frequencies?
No, no, and completely separate.
CWatters
#3
May5-13, 10:38 AM
P: 3,239
Understanding the spectrum of frequencies
What is the distinction between EM waves and Sound waves.

I know that sound is cyclical vibrations in some sort of medium. When the frequency increases, do these vibrations become EM waves?
No. The method by which energy propagates is totally different.

I think what's confused you is that they are sometimes shown on graphs that show sound down one end and light at the other. All these scales are trying to do is show the relative frequency range they occupy HOWEVER they don't do a very good ...

For example lightning generates both sound and electromagnetic waves in the 0-10KHz range. You can hear the sound waves because the ear is designed to detect air pressure waves. You can't hear the EM waves even though they are in the same frequency band because the ear is not a radio reciever. The sound waves produced by lightning propagate a relatively short distance through the air whereas the EM waves can be detected thousands of km away.... if you have a radio reciever that convert the EM waves produced by lightning radio waves into sound waves..

http://theinspireproject.org/default.asp?contentID=1

So..

Are sound and EM waves completely seperate things, or are they the same things but at different frequencies?
They are different things.

They can be at the same frequency or different.

Jacobim
#4
May22-13, 10:34 AM
P: 23
Understanding the spectrum of frequencies

Could it be said that the eye is a radio reciever?
CWatters
#5
May23-13, 05:50 AM
P: 3,239
Only (?) in that it also detects electromagnetic waves.

I believe the detection mechanisim in the eye involves complex chemical reactions rather than purely electrical processes.
phinds
#6
May23-13, 06:34 AM
PF Gold
phinds's Avatar
P: 6,487
Quote Quote by Jacobim View Post
Could it be said that the eye is a radio reciever?
No, "radio" is a specific band of the electromagnetic spectrum and the human eye does not respond to those frequencies.


Register to reply

Related Discussions
Negative frequencies in spectrum analysis..... Electrical Engineering 7
Understanding what natural frequencies mean(specifically in 2deg. of freedom system.. Classical Physics 0
Relationship between relative frequencies of electromagnetic spectrum and sound General Physics 2
Can the Visible Spectrum be Seen on an Antenna Oscillating at one of the Frequencies? General Physics 2
Understanding of Bandwidth was that it is the Range of Frequencies Electrical Engineering 7