How Many Photons in a Light Wave

In summary, the concept of a single photon is equivalent to a single light wave, and vice versa. A single photon is considered a tiny instantaneous part of a light wave and can be thought of as a stream of photons all hitting a surface with the same frequency as the light wave. The localization in space or time of a light pulse is due to the superposition of many modes closely spaced in frequency. It is theoretically possible to send a pulse into a material and get a continuous wave out the other side.
  • #1
peter.ell
43
0
I was just wondering how the concept of a single photon is compared to the concept of a light wave.

Is a single photon equivalent to a single light wave, or is a single photon just a tiny instantaneous part of a light wave? That is, if a single light wave of a given wavelength strikes a surface, would that surface respond as if only one photon hit it, or a stream of photons all hitting it with the same frequency as the light wave?

Or am I completely mis-understanding this and it's neither of these two? Please help me understand this conceptually.

Thank you so much!
 
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  • #2
A single photon is what you would call a light wave, and vice versa.
 
  • #3
Excuse me if I make a bunch of over-simplified statements.

Does a single photon have a beginning and an end? Whenever I think of light pulses I think of the localization in space (or time) as being due to the superposition of many modes closely spaced in frequency. If the light were truly monochromatic it would have to extend infinitely in time. I can send the pulse through an absorptive medium such that most of the light gets absorbed every time. If I repeat this enough times, for one of these pulses everything is absorbed except for a single photon (hv of energy). Then is it theoretically possible to send a pulse into a material and get a continuous wave out the other side?
 

1. How are photons related to light waves?

Photons are tiny particles that make up light waves. They are the fundamental units of light and carry energy and momentum.

2. How do we measure the number of photons in a light wave?

The number of photons in a light wave can be measured using a device called a photometer. This device counts the number of photons hitting a surface in a given time period.

3. Is the number of photons in a light wave constant?

No, the number of photons in a light wave can vary depending on the intensity of the light. Higher intensity light will have more photons, while lower intensity light will have fewer photons.

4. Can we see individual photons in a light wave?

No, we cannot see individual photons with the naked eye. They are too small and move too quickly for our eyes to detect. However, we can indirectly observe their effects through experiments and technology.

5. How does the number of photons in a light wave affect its wavelength and frequency?

The number of photons in a light wave does not affect its wavelength or frequency. These properties are determined by the energy of the photons, which remains constant regardless of the number of photons present.

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