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# light as a wave Tweet

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1. light as a wave
if you model light as a wave, what does the amplitude represent?
2. electric / magnetic field magnitude
3. what would that be equivalent to in the particle model?
the energy of photons?
4. the quantum particle model?

it would be the probablity amplitude
5. yeah yeah,I'd love to know too,I'm doing quantum physics this year and I would really appreciate talking about the subjects,so you two go a head talk about the theorypretend as if I'm not herego on
6. (Original post by elpaw)
electric / magnetic field magnitude
as there is always a magnetic field with the electric field,which both are perpindicular to each other,though I wonder how does it happen,I mean how do they affect the amplitude,any good site that could explain that eplaw??
7. amplitude equiv of quantum = number of photons per unit area
8. *stares blankly*
9. (Original post by mik1a)
if you model light as a wave, what does the amplitude represent?
The amplitude is a measure of intensity or brightness, measured in lumems, or in power....watts per meter squared.
10. surely the frequency affects the intensity, as higher frequencies deliver more energy?
11. (Original post by mik1a)
surely the frequency affects the intensity, as higher frequencies deliver more energy?
Frequency affects the color.
Lower frequencies = infra red
higher frequencies = ultra violet
the visible spectrum is between the above two.
12. i think mik1a is talking about E = hf, in which case yes, intensity depends on frequency (if the number of particles per unit time is kept constant)
13. now from my A2 experiance I know that intensity depends on number of electrons emitted per second(phtotelectric emission) and that frequancy affects the photon energy recieved
14. (Original post by elpaw)
the quantum particle model?

it would be the probablity amplitude
You are thinking of the wavefunction, which is a complex wave, that doesn't exist in reality. We are talking about real electromagnetic waves, and what their wave properties i.e amplitude represent in the particle model.
15. so youre asking what the field magnitude represents in the particle model?
16. yeah
if you have a ligh wave with amplitudse a, what does a mean when you consider that light is made of photons with certain energies?
18. I would say amount of photons. Because the energy of a wave is proportional to the amplitude squared, and the energy of photons is proportional to the frequency, a bigger amplitude means more energy and hence more photons are required in a given volume, or area.

So basically i'm voting in favour of Willa's explanation.
19. I has to do with the intensity,I asked my physics teacher and she told me today
20. (Original post by mik1a)
if you model light as a wave, what does the amplitude represent?
The amplitude represents the intensity, which in the particle modell would correspond to the number of photons. It is the frequency that corresponds to teh energy of each individual photon.

This is seen in the photoelectric effect experiment. If you double the intensity of the UV light, then you double the current flowing through the vacuum tube, but you do not change the stopping voltage. If you double the frequency then you double the stopping voltage, but you do not change the current. The intensity (which is determined by the amplitude) determines how many photons you have, whereas the frequency determines what energy each individual photon has.