1 upvotes, 4 direct replies (showing 4)
View submission: Ask Anything Wednesday - Engineering, Mathematics, Computer Science
I think the way noise cancelling headphones work is fascinating! Are there any other areas besides sound where waves are canceled? E.g. radiation in space, light, magnetism, electricity..?
Comment by chilidoggo at 24/07/2024 at 18:18 UTC*
6 upvotes, 0 direct replies
Pretty much all waves act like this, but the lower the frequency (aka the longer the wavelength) the easier it is to line them up in that manner. If you look up "destructive interference of _____ waves" and plug in light, radio, whatever you'll see plenty of examples. Probably not for magnets since that's a force not a wave, but who knows.
One thing to keep in mind is that destructive interference is just the opposite of constructive interference, except constructive is, IMO, more useful. Lasers, microwaves, etc. all rely on constructive interference to amplify a single wavelength for a specific purpose. Destructive is planned around - for example see the positioning of radio towers.
Comment by Weed_O_Whirler at 24/07/2024 at 18:12 UTC
5 upvotes, 0 direct replies
Tons of them.
One example, AESA radars use constructive and destructive interference to steer radar beams[1].
1: https://en.wikipedia.org/wiki/Active_electronically_scanned_array
Comment by agaminon22 at 24/07/2024 at 19:30 UTC
3 upvotes, 0 direct replies
The general phenomenon you're looking for is called interference, and it is a property of essentially all waves. This includes sound and other mechanical waves, but also light and even "quantum waves".
Interference arises from linearity but it is inherently nonlinear. This may seem contradictory, but it is not since the linearity and nonlinearity refer to different aspects. "Linearity" means that adding two waves gets you another wave. In the case of noise-cancelling, you add two "opposite" waves to get as close as possible to no sound. The nonlinearity appears because the intensity of a wave is proportional to the *square* of the wave. So when you add two waves and calculate the square, you get extra terms since (a+b)^2 is not a^2 + b^2 .
Comment by Roman_from_Bhooks at 24/07/2024 at 19:43 UTC
1 upvotes, 0 direct replies
Thanks for all the answers - I now know what topics to research for further understanding, much appreciated!