Exploring Light: The Wave Perspective

In summary, from a particle perspective, the smallest increment of light is a photon with energy dependent on its frequency. From Maxwell's wave perspective, light propagates through the exchange of energy between the electric and magnetic fields. The frequency of the wave is determined by the rate at which this exchange occurs. However, a short wave pulse cannot be a pure sine wave and will contain higher frequencies. This is why it is important to understand classical E&M before delving into the concept of photons. Mathematically, this can be described using Fourier transforms and the properties of the ether.
  • #1
God Plays Dice
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Trying to understand small increments of light.

From a particle perspective, a photon is the smallest increment, dependent on frequency as E=hf.

From Maxwell's wave perspective, light propagates as a result of the energy passing between the E field and the B field. The rate at which this occurs gives the frequency.

So from a wave perspective, how short can a wave of light be? Less than one wavelength?

If I have a source, a radio transmitter, that emits 10 1/4 lambda of light, and 10 lambda is received/filtered/reflected, can the 1/4 that's left when the filter is removed still propagate?
 
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  • #2
God Plays Dice said:
Trying to understand small increments of light.
Think some more about classical E&M before you worry about photons.

God Plays Dice said:
From Maxwell's wave perspective, light propagates as a result of the energy passing between the E field and the B field. The rate at which this occurs gives the frequency.
Nope, that's not the way an EM wave works. The energy does not pass from E to B and back again. E and B are in phase. At the crest of the wave, E and B are both maximum simultaneously. Ninety degrees later, at the node, they are both zero simultaneously. The energy density is E2 + B2. That means there is plenty of energy at the crest, shared by E and B in equal amounts, and none at all at the node.

God Plays Dice said:
So from a wave perspective, how short can a wave of light be? Less than one wavelength?
A short wave pulse cannot be a pure sine wave. If you cut off a sine wave into a short pulse, the wave will no longer be pure, it will contain high frequencies. Frequencies so high that their wavelength is comparable to the pulse length.
 
  • #3
So if you cut monochromatic laser light off it will change frequency?
 
  • #4
Example, an extremely low frequency em wave, 0.1hz, if you take a 2.5 second burst is it not photons present in a 1/4 wavelength of a sinusoidal charge/magnetic field?
 
  • #5
laser light^
 
  • #6
I'm thinking about it in terms of a particle accelerator. If I use the 1/4 lambda above can I aim that at a proton and get it to accelerate due to the charge wave?
 
  • #7
God Plays Dice said:
So if you cut monochromatic laser light off it will change frequency?

Yes, just as the shape of water waves will change if you do something to disturb their propagation. This is one of the reasons that Bill_K is advising you to understand classical E&M before you try thinking in terms of photons.
 
  • #8
Alright. So can I read any math that will describe this? the limit of the existence of the wave? The other effect I was interested in is the faraday effect... how sharply/irregularly can I twist a linearly polarised wave and keep it as propagating light?
 
  • #9
Feels like what I am looking for are the mechanical properties of the ether?!
 
  • #10
God Plays Dice said:
Alright. So can I read any math that will describe this?

Bill_K's reply in post #2 seems intuitive enough:
A short wave pulse cannot be a pure sine wave. If you cut off a sine wave into a short pulse, the wave will no longer be pure, it will contain high frequencies.

Try this: Draw a sine wave with one full frequency cycle. Now remove/erase as much of the sine wave as you want to represent a shorter pulse. When you're done erasing, draw/add vertical extension(s) to the curve that remains to connect to the zero 'node' axis. Now do you see why fractions of frequency pulse result as Bill_K described?
 
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  • #11

1. What is light?

Light is a form of electromagnetic radiation that is visible to the human eye. It is made up of tiny particles called photons that travel in waves.

2. How does light travel?

Light travels in straight lines at a speed of approximately 299,792,458 meters per second. It can travel through a vacuum, as well as through transparent materials such as air, water, and glass.

3. What is the wave perspective of light?

The wave perspective of light is the idea that light is made up of electromagnetic waves that can be described using properties such as wavelength, frequency, and amplitude. This perspective helps us understand how light behaves and interacts with its surroundings.

4. What is the electromagnetic spectrum?

The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation. This includes all types of light, from radio waves to gamma rays.

5. How does light interact with matter?

Light can interact with matter in a variety of ways, including absorption, reflection, and refraction. These interactions are determined by the properties of the material, such as its transparency and density.

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