Particle Physics (34 of 41) What is a Photon? 18. Amplitude vs Intensity - How "Big" is a Photon?
Vložit
- čas přidán 27. 05. 2015
- Visit ilectureonline.com for more math and science lectures!
In this video I will explain how the concept of how “big” is a photon with respect to its energy, wavelength, and energy transfer.
Next video in the Particle Physics series can be seen at:
• Particle Physics (35 o...
Excellent! Thank you so much for making these concepts easy to understand. This certainly helps.
Glad it was helpful! 🙂
Using Planck's equation where Energy = hf the units of h are Joule-sec and the units of f are cycles/sec. Dividing both sides of the equation by "cycles" yields Energy/cycle = Joules. Therefore a photon is a single cycle of the electromagnetic wave equal in length to a single wavelength (lambda), not a continuous wave or a "packet" of energy as often stated.
Thank you! It cleared a lot of confusion I was in.
That's cool, except that it's completely false. Nobody has ever seen "a single cycle" of an em wave. If we had, it would have had a smeared out spectrum per Fourier transform and not a well defined energy to begin with.
Saved my day. I respect your videos as they have helped me big time.
Glad to be of help
Where can i get more information on wavefunction?
Hi. It's a very intersting video. Would you have any knowledge of other video on this topic (size of photons, the way an electrons "feels" ad reacts to electromagnetic wave) ?
Anyway, it's a shame you don't have more followers ...
NicosM51
Interesting you asked. I am currently preparing to show videos on how an electron is affected by the oscillating electric field and oscillating magnetic field of the photon. They should by up in a few weeks.
If people pass the word, more followers will come.
very good explanation...thanks for sharing knowledge with the human society.I have a question..Does a single photon travel in 2 dimension(like in polarized light....The electric field i mean)?
Depending on the source of the electromagnetic radiation. For example the light coming from the Sun will oscillate in all directions perpendicular to the direction of travel due to the randomness of the movement of the atoms generating the radiation.
+Sil Mov . See my comment here. I'm an amateur scientist myself.
What is the correlation between an oscillating electric field and a molecule's ability to absorb photons? If the molecules do not absorb the incoming photons, are they not affected by the oscillating electric field?
+Tyrone Slothdrop
That is correct.
Is it really Emax of the electric field produced by one photon? Or since this lecture we speak about superposition of the electromagnetic fields induced by closely flying photons? I.e. higher the density of photons is, higher Emax is.
That is a good question. The particle - wave duality is a tricky thing to understand. We plan on making videos on that exact topic, but they are still in the preparation stage.
@@MichelvanBiezen There is nothing tricky about it. It doesn't even exist. It's just a remnant of poorly understood 1920s physics when they didn't know about field quantization, yet.
A photon is depicted as an oscillating electric & magnetic field confined in a 2 dimensional travelling sine wave which does not occupy any space. At the same time photon is a real physical entity which can carry energy, momentum & can also produce pair of mass bearing particles. Are photons made of space just as water waves are made of water. Can only fields i.e. electric, magnetic & gravitational travel at light speed. In water waves wave energy is carried by water molecules how is energy in electric field carried. Anything which can carry force, energy & momentum has to have some kind of physical nature.
Water waves are no made of water. Water is the medium, waves are the energy traveling through the medium.
how we can find the amplitude of an electromagnetic radiation???
This playlist will answer a number of your questions: PHYSICS 50 ELECTROMAGNETIC RADIATION
Sorry that I am coming to this one a little late as it is 2022 now but as you answered some body just 3 months ago I will put my 5c worth in anyway. First your intensity formula is for field strength of an omni directional signal. The signal can be made directional and there fore much stronger. In my opinion this is not one Photon but billions of photons. I have a table giving Wave length, Frequency and energy of Photons. I believe that one Photon has the same energy from it's birth to its death regardless how far it goes. If it dies or just combine with an electron when it makes an electron jump in an atom I don't know. The energy of the Photon get's absorbed by the jump.
What I think may be a better way to think about a Photon is as a pulsating blob. The size could have some thing to do with the wave length. It can only move in one direction unless some thing is pushing it in a different direction. It is not going omni directional at all
With the double slit experiment then are we really sure that it is not multiple photons interfering with each other? Reflecting Radio signals interfere with each other and that is with a delay much longer than the frequency as well as parts of the frequency. I don't think our detectors are sensitive enough to detect just one Photon.
Photons don't have a wavelength. Only classical electromagnetic waves, which are the averages of many photons, have a wavelength. Photons don't exist independently of an irreversible process (either emission or absorption). What photon energy and momentum we are measuring depends on the characteristics of those irreversible processes. One can do plenty of optical experiments to demonstrate that. Simple Doppler effect changes "photon energy". Interference is the complete absence of interaction. A sentence like "multiple photons interfering" does not even make borderline logical sense. I understand that you are confused. That confusion stems from a constant bombardment with completely false information about quantum optics. You need to forget everything you know and read a few good textbooks on these topics.
I wonder what is "P" from the I=P/A equation. Is that Electromagnetic Pressure by chance?
P stands for "power". A = area The intensity = (power of the source) / (area over which the energy spreads)
@@MichelvanBiezen oh, now that makes sense. Thank you for the reply. I wasn't expecting it so quickly! You're truly helping the community with your implication :)
Thank you and glad to help.
I'm sorry I'm just not understanding why, If we can describe the wavelength of a photon then why can't we describe the waveheight?
When we calculate the wavelength, it is associated with the wave properties of electromagnetic waves. We assume that the photons have the same wavelength. But the magnitude of the oscillations, cannot be confined to that of a single photon and again becomes the property of the electomagnetic waves.
I still don't get it.
Can someone explain how the electromagnetic wave shape of one oscillation of an electron at the source look like? Is the result one photon with an electromagnetic wavefront of one wavelength? Or is it multiple wavefronts? Is the typical depiction of multiple wavesfronts a depiction of multiple oscillations behind each other or just one? Is it irrelevant? I'm going crazy over this.
1 oscillation = em wavefront with a wavelength = 1 photon?
1 oscillation = em wave of multiple wavefronts with respective wavelenghts = 1 photon?
Those are great questions! That is why it is so difficult to understand what a photon is. Thus the approach we took, was to look at all the properties of E&M radiation and the singular photon and try to deduce it that way. A single photon is thought of as a "wave packet", which would mean that it would include both the electric field and magnetic field oscillations in a small packet consisting of several wave lenghts. Not sure that I agree with that yet.
@@MichelvanBiezen Very confusing. Thanks you for answering.
Why is it so hard to determine this?
I can't wrap my head around why we are able to mesure a wave length but not definitively say (in laymens terms) how many hills and troughs one oscillation cycle produces through it's given/ radiated energy.
I mean a mechanical wave, through an apple falling into water, produces one wavefront with one wave length if we assume that we don't account for the water oscillating up and down.
If one photon is part of a wave packet, my brain tries to picture the electron oscillating multiple times because of the multiple incoming hills and troughs of the external photon to then radiate a new wave packet of the same energy and wave packet size.
Because up until now I strongly thought that the frequency is the time between oscillations of the source electron which would completely depend on how heavily the source is bombarded with energy/external photons.
Though what you say is that it is thought to be one oscillation per photon and regardless of how many times this oscillation at the source happens, the created em wave of one oscillation is in and of itself a wave packet with x many oscillating wave lengths and comprised of an electric and a magnetic field respectively with a frequency of trillions in that packet?
I would appreaciate if that thought could be clarified. Maybe I'll be able to stop thinking about this for a while then :D
I didn't say that it was one oscillation per photon. Each photon does have a particular frequency. It is believed that a photon is like a wave packet which contains multiple oscillations.
@@MichelvanBiezen I see.
Thank you :)
An electron is a quantum of energy. It does not have an associated wave shape. That's a classical phenomenon that doesn't exist at this scale.
I've been pondering this very question: What exactly is "waving" in photonic electric and magnetic fields? My best guess is to give the electric field dimension=5 and magnetic field dimension=6. Therefore you have x, y, and z for 3 dimensions, time as 4th dimension and both the electric and magnetic fields making a total of 6 dimensions. The math can get quite interesting...
~1V per mm (E of sunlight)
Yes it is.
Where did you get that bullshit from? :-)
A photon is a little bit of electromagnetic field energy. Energy doesn't have a size.
Instead of the words "little bit", it may be more appropriate to use the word "piece" or "segment", and as such we can describe the physical characteristics of that "piece".
@@MichelvanBiezen It is not a piece. One can not break an electromagnetic field into distinct parts like a physical solid breaks into atoms. "a little" simply means that for optical photons we are talking about something on the order of 3e-19J, which is a small amount of energy compared to macroscopic energy values.
Einstein received the Nobel prize for proving that electromagnetic waves are made up of individual "particles" which we call photons.
@@MichelvanBiezen OK, now you have to go back to middle school and re-learn that science is not what famous people say. Science is the rational description of nature. Einstein's 1905 paper on the photoelectric effect does, indeed, contain a mistake. He talks about photons having position properties and that is entirely wrong. Nobody has ever been able to assign a position to a photon. Not before that paper was written and not since.
Just because you can find a mistake in a scientific paper doesn't invalidate the premise of the paper, that light is indeed quantized.
Not hard to see how mans wireless communications and remote sensing is warming the atmosphere . Did you know ,the first microwave oven was called a RADAR range .
Yes, i did. (I was a radar engineer fo 30 years). But the communication does not heat up the atmodphere. If it did, the commumication wouldn't work.
@@MichelvanBiezen Thanks for you reply, How many radio and microwave transmitters are in use around the world emitting photons into the atmosphere 24/7 (photons = Heat) Radio and microwaves are not absorbed in the atmosphere rather they excite and heat the atmosphere via molecular vibrational heating and photon propagation.
"9.3 photonic mist
When we look at a diagram released by 13EMF Portal, we realize that humans are creating artificially very long
waves that otherwise would not be present, and we know that it is a photon that is heat and nothing else.
Humans are creating waves as long as 10 000 kilometers, a kind of wave that would be naturally blocked by
the earths atmosphere. Commercial radio waves can be as long as 100 kilometers, they have a lot of heat
energy. It would thus be unfair to not look at the composition of the atmosphere in terms of quality of photon
presence to fully understand climate change. Every cellphone signal could potentially be responsible for
increasing the heat in the atmosphere. These waves are blocked from coming in, they will certainly be blocked
from the same electrical charges from leaving.
The photonic mist is man made photons in the atmosphere. They must contribute to global warming if such
an event is taking place."
www.researchgate.net/publication/331083514_What_is_Heat_The_Photon_is_Heat
Electromagetic waves can only add "heat" to the atmosphere if they can be absorbed by the molecules in the atmosphere. We choose the wavelengths of our communication devices the stay out of the absorption windows otherwise if they were easily absorbed by the molecules in the atmosphere they wouldn't get very far. That is why most of the energy emitted by the communicaiton devices does not add heat to the atmosphere.
@@MichelvanBiezen Convection is one form of heat transfer but microwaves don't heat via convection rather they use electrical conduction and resistance to heat things up . Weather radars bounce/reflect 2.4 GH off the water molecule to excite it and release a photon/electrons (electrical energy) back to a ground state picked up by a receiver on the ground. You force a electron beam (RADAR) through a medium of electrons under 1 bar of pressure (the atmosphere) and you have to have some form of electrical resistance and excitement = HEAT . I see photons as a nano electric spark that's why when you look up in the day time we see the sky a plasma blue as the suns photons/electrons carry enough energy (momentum) to ionize (spot weld) oxygen to form ozone .