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Re: [Phys-l] remotes



On 11/4/2011 2:43 PM, Anthony Lapinski wrote:
I'm teaching about EM waves in astronomy and atmospheric absorption. I use
a remote control, solar cell, and Radio Shack amp/speaker to show that
remotes give IR pulses. These waves are partially blocked by a black
plastic bag and almost totally blocked by white paper or aluminum foil.
They go right through wax paper, clear plastic, and a metal screen.

Does anyone know the frequency (wavelength) range for typical remote
controls (for radios, TVs, DVD players, etc.)?

On a related note, my car remote pulses go through walls. Are these waves
similar to those for remotes I mentioned earlier, or is it in a different
part of the EM spectrum? I have not tried my shields with my car remote
yet.

Any other demos that can be done with these remotes?

_

One "Universal" car remote on offer specifies a range of
UHF 303-433MHz (69cm -- 99cm)

I ran across one TV remote specified at NIR ~300 THz ( 980nm)
Interesting that one radiates at a million times the frequency put out by the other.
They are both encoded of course.
(It's not been so long since pranksters would drive slowly
down the street opening garage doors at will.)

Besides the serious use to which cams fitted with visible light stop filters can be put,
there was something of an adolescent cottage industry in revealing peoples'
underwear- still not as nefarious as the perverted use of cams to take up
shots and down shots in various places, nor as revealing as taking a
walk through an airport.

Brian Whatcott