The discussion revolves around the differentiation between electromagnetic (EM) waves and photons, exploring their nature, relationship, and implications in various physical phenomena. Participants express confusion over these concepts, seeking clarity on their definitions and roles in physics.
Participants express a mix of views, with some advocating for the importance of understanding both EM waves and photons, while others suggest focusing on one concept at a time. There is no clear consensus on the best approach to learning these topics, and disagreements arise regarding the necessity of understanding photons at the current stage of study.
Participants acknowledge that the study of photons involves more advanced concepts, such as quantum electrodynamics, which may not be accessible at the current level of understanding. There are also references to common misconceptions that may arise due to limited mathematical knowledge.
This discussion may be useful for students and learners in physics who are trying to understand the foundational concepts of electromagnetic waves and photons, particularly those at the introductory level seeking clarity on these interrelated topics.
Try to forget that you ever heard the word "photon" until you're done studying electromagnetic waves. Photons are part of the theory of quantum electrodynamics (quantum mechanics meets relativity meets electrodynamics) which you won't get to for several years to come.Karan Punjabi said:Guys, I am studying about electromagnetic waves and I'm not able to differentiate between a photon and a em wave or I'm not understanding it. Please help me to solve it out. Thanks
Karan Punjabi said:Guys, I am studying about electromagnetic waves and I'm not able to differentiate between a photon and a em wave or I'm not understanding it. Please help me to solve it out. Thanks
The wave theory of light=diffraction/interference theory is very important for doing any kind of modern physics where things like diffraction grating based spectrometers and thin film optical (bandpass) filters are in widespread use as research tools. The theory behind these is for the most part classical electromagnetic wave theory.Sturk200 said:They are two different ways of modeling the same phenomenon, namely light. One is continuous (waves), the other is quantized (photons). I think it's right to say that photon theory is more complete than wave theory, as it is able to account for things like the photoelectric effect. But wave theory is still "illuminating," if you will.
Sturk200 said:They are two different ways of modeling the same phenomenon, namely light. One is continuous (waves), the other is quantized (photons). I think it's right to say that photon theory is more complete than wave theory, as it is able to account for things like the photoelectric effect. But wave theory is still "illuminating," if you will.
. One is continuous (waves), the other is quantized (photons).
Ohk that means I shouldn't go for photons right now.But how should I imagine a EM waves, just as a wave? So in photoelectric effect can i study it without the term photon?Nugatory said:Try to forget that you ever heard the word "photon" until you're done studying electromagnetic waves. Photons are part of the theory of quantum electrodynamics (quantum mechanics meets relativity meets electrodynamics) which you won't get to for several years to come.
So at this level what should i do? Can i understand photons?Sturk200 said:They are two different ways of modeling the same phenomenon, namely light. One is continuous (waves), the other is quantized (photons). I think it's right to say that photon theory is more complete than wave theory, as it is able to account for things like the photoelectric effect. But wave theory is still "illuminating," if you will.
But now i simply want to differentiate or to understand EM wave or photonCharles Link said:In studying EM waves, you also will learn that the energy density of the electromagnetic waves (and also the power/unit area incident onto a surface) is proportional to the second power of the electric field amplitude. This energy is proportional to the number of photons. (Photon energy Ep=h*f). By computing the energy, you can calculate the number of photons. If you are studying diffraction and interference theory, it helps to have at least a partial understanding of what the photons represent. There is a wave-particle duality, but the energy and photon count is conserved in an interference pattern.
The study of photon is much more elaborate and richer than what you may think it is. For your current stage of study, I suggest that you hold onto the understanding that photons are the entity that is responsible to the energy unit of an electromagnetic radiation. Namely, given the frequency of the radiation, its total energy can be expressed as an integer multiple of the one photon energy corresponding to this frequency.Karan Punjabi said:But now i simply want to differentiate or to understand EM wave or photon
davenn said:it's not just related to light ... it is for the whole EM spectrum !
davenn said:then you don't quite understand what photons are
Karan Punjabi said:So at this level what should i do? Can i understand photons?
Yeah I'm understanding it. Will try to grasp moreblue_leaf77 said:The study of photon is much more elaborate and richer than what you may think it is. For your current stage of study, I suggest that you hold onto the understanding that photons are the entity that is responsible to the energy unit of an electromagnetic radiation. Namely, given the frequency of the radiation, its total energy can be expressed as an integer multiple of the one photon energy corresponding to this frequency.
I would also like to warn you in advance about a common misconception in this matter so that you won't fall for it, is that people with limited mathematical knowledge of photons tend to easily associate the wavefunction of photons with the electric (or magnetic) field disturbances. That's not true, because in the quantum description of light, electric and magnetic fields are operators, hence they are a different and separate object as photon's wavefunction.
If you dive deeper in this direction, you will also learn that the energy of an electromagnetic radiation, despite expressible as an integer multiple of a photon's energy, can also have some uncertainty due to the uncertain nature of the number of photons contained in that radiation.
Lastly, if you feel like the second and third paragraph of my post is taking too long or too abstract to grasp, then you do need to hold for the time being your complete description about the difference between the EM wave and photons to the basic level, for which the first paragraph of this post shall be representative.
Sturk200 said:Some folks say "light" and mean electromagnetic radiation. I'm one of those folks.
Come on, you can't just say something like that without saying why you're saying it.
Probably to fully understand photons you have to study quantum electrodynamics directly, and to study quantum electrodynamics you have to study quantum mechanics, and probably before you study quantum mechanics you should study classical mechanics and electrodynamics, so probably you won't be able to understand photons for a little while. I know I don't fully understand them yet and I'm on my second semester of QM. But you can still learn the basics, like that the energy is frequency dependent, and that their behavior is probabilisitic, and all the other stuff they write about photons in intro physics books.
Plus you can watch them shoot through a bottle!
Karan Punjabi said:I didn't understand what the video is all about?
Okay...Sturk200 said:They made a camera that is so fast that it can make an image of light in motion. That's all...