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Intensity of Light using Quantum theory

  • #1

Homework Statement


Approximately 4% of the intensity of light is reflected at a glass-air boundary. Classically one expects roughly 8% of light to be reflected from a thin glass plate (4% at the front and back boundary). Outline briefly what quantum theory predicts for a single photon instead of a light beam, in particular, say how this differs from the classical prediction.

2. The attempt at a solution
If light shines on an imperfectly transparent sheet of glass it may happen that 96% of light transfers through the glass, this makes sense if light were a wave, as the wave splits and a smaller wave is reflected back. But light is considered as a steam of particles so the glass has a 96% chance of being transmitted and 4% chance of being reflected. The behaviour of the photon is totally random and unpredictable. It is defined as a wave function. A particle when not being measured or located takes the form of a field of probable locations some being more probable or as likely than others.

Is that right?
 

Answers and Replies

  • #2
215
21
Your answer is not wrong but it is not clear.
They are demanding the behavior of a single photon. So I would advise to clean up this part:
If light shines on an imperfectly transparent sheet of glass it may happen that 96% of light transfers through the glass, this makes sense if light were a wave, as the wave splits and a smaller wave is reflected back. But light is considered as a steam of particles so the glass has a 96% chance of being transmitted and 4% chance of being reflected.
I couldn't quite get what you wanted to say.

Then I would skip that part:
The behaviour of the photon is totally random and unpredictable.
since it is not correct. It is true that the behavior follows a probabilistic behavior, but that does not mean that it is "totally unpredictable". However, saying that It is described by a wavefunction suffices. And the last sentence is also good.

When you correct the first part maybe move it after the second one. You would then have explained the general quantum behavior and moved on to the specific problem.
 

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