Brightness of light & light model

[wavingerwin]

I have been wondering
1. We know that light has a wave-particle duality. Does the "light" here mean electromagnetic radiation, or just visible lights?

2. If it EMR exhibits wave-particle duality, does that mean radio waves are transmitted in form of photons?

3. and finally, I was reading through one of the posts and quoted:

In visible light amplitude is brightness and frequency is color

Isn't the brightness in visible light dependent on the number of photons the stream of light has? (not the amplitude)

Thank you very much!

 

[mgb_phys]

I have been wondering
1. We know that light has a wave-particle duality. Does the "light" here mean electromagnetic radiation, or just visible lights?

All electromagnetic radiation is made of photons, either small high energy ones in x-rays or long low energy ones in radio waves.

In fact all matter has a wave-particle duality it's just that the wavelength depends on the momentum of the object. For real world objects like a tennis ball the momentum is large enough that the wavelength is very small - so we only see the effect with very small objects like photons and sub-atomic particles.

[/QUOTE]Isn't the brightness in visible light dependent on the number of photons the stream of light has? [/QUOTE]
It depends on the number of photons/sec. However brightness for something seen by your eye also depends on the wavelength since your eye is more sensitive to certain wavelengths (colors).

 

[wavingerwin]

Since the brightness is dependent of the number of photons per sec

So the amplitude of the wave doesn't do anything?

 

[Andy Resnick]

Photon number is non-conserved, so connecting the number of photons to the field amplitude is non-trivial. "Brightness", in addition, has a specific definition in radiometry that is different from how the term is being used here. "Intensity" or would be a better term.