Interference

[Lance]

Somebody recently told me that two electromagnetic waves in the same place ALWAYS combine to create a new wave.

 

If this is true why don’t radio waves and other electromagnetic waves combine with light, effectively changing the color?

[AntiMagicMan]

The light waves need to be the same frequency, but radio waves and visible light have massively different frequencies.

[swansont]

The light waves need to be the same frequency, but radio waves and visible light have massively different frequencies.

 

It's true that the sum of the frequencies would be only a very small change, but you need more than just having two waves of similar frequencies. You have to combine the photons in some nonlinear material. You can then generate photons with the sum and difference frequencies. One common use of this is frequency doubling - take two photons at frequency w and combine them to generate a photon at 2w.

[Lance]

Somebody recently told me that two electromagnetic waves in the same place ALWAYS combine to create a new wave.

 

 

So would this be an incorrect statement?

[swansont]

Somebody recently told me that two electromagnetic waves in the same place ALWAYS combine to create a new wave.

 

So would this be an incorrect statement?

 

No, the waves add. You get interference, though. Beat notes. If the waves are of exactly the amplitude, the new amplitude will double at that point and the light will be twice as bright, but not at a new frequency (which is what would be required to get a new color)

[YT2095]

a similar principle applies in Radio, it`s called hetrodyne (sometimes refered to as SuperHet).

it also woks on beat frequencies called "side bands". and can also be used in a cancelation format. ie/ in CW receivers

[swansont]

a similar principle applies in Radio' date=' it`s called hetrodyne (sometimes refered to as SuperHet).

it also woks on beat frequencies called "side bands". and can also be used in a cancelation format. ie/ in CW receivers [/quote']

 

Yes, but interference is a spatial beat note. Heterodyning requires a mixer of some sort to generate sum or difference frequencies.

[Lance]

I think you guys are missing the word "ALWAYS".

 

Would a gamma and radio wave add?

[swansont]

I think you guys are missing the word "ALWAYS".

 

Would a gamma and radio wave add?

 

The waves add, as I already said. As far as creating a "new" wave, it depends on what you mean by that. That goes for gamma and radio - but you're adding waves that are perhaps ten orders of magnitude different in frequency, and it's not going to look like much is happening.