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...
EM waves, or electromagnetic waves, are a type of energy that travels through space in the form of oscillating electric and magnetic fields. Photons are the fundamental particles that make up EM waves.
EM waves are unique because they do not require a medium to travel through, unlike sound waves. Photons, on the other hand, have no mass and travel at the speed of light, unlike particles with mass which cannot reach the speed of light.
EM waves carry energy from one place to another. The energy of an EM wave is directly proportional to its frequency, meaning that higher frequency waves have more energy. This is why higher frequency waves, such as gamma rays, can be more harmful to living organisms than lower frequency waves, such as radio waves.
EM waves and photons have a wide range of applications in our daily lives. They are used in communication technologies, such as radio and television, as well as in medical imaging, like X-rays and MRI scans. They also play a crucial role in generating and harnessing energy from sources like the sun and nuclear power.
While EM waves and photons have many beneficial uses, they can also be harmful in high doses. For example, exposure to UV radiation from the sun or X-rays in medical imaging can damage DNA and lead to health issues. It is important to understand and limit our exposure to these types of waves and particles.