A few questions?

[Stratus]

These are all questions about light, so I figured it would go here?

First off, I've heard that perpendicular electric and magnetic fields create EM waves, but why is that? what happens that forces those waves into existence just from perpendicular fields?

Also, since light is an EM wave, does that mean that it is also created from these fields? Because when I read about light, it was always said to be created when electrons jump around locales.

 

Also, not related to this subject, I'm rather new to physics and I've read a few books on quantum theory and enjoyed them, but, as I read through some of the topics on this forum, I was completely lost.

 

May I ask if this is normal for someone new to physics, or if I'm sure being really dense? Such as, I'm rather confused with quantum superpositions. I understand most everything about schrodinger's cat, but how is this useful in real life quantum physics? I mean, what causes things to be in a superposition? Is it more of a mental state, or is it something we can measure?

What I mean by this is, how can we tell if something is in a superposition?

Thank you for taking the time to read this, I'm very interested in quantum physics and physics in general, but where do I start?

 

-Stratus.

[elfmotat]

To answer your question about EM waves, this is all explained by Maxwell's equations. Boiled down, what they say is that a changing electric field will produce a perpendicular magnetic field, and that a changing magnetic field will produce a perpendicular electric field. So basically what happens is that you start with an oscillating electric field, which makes a magnetic field, which makes an electric field, etc. You end up with sinusoidal electric and magnetic fields, which travel at precisely the speed of light.

 

As far as your questions about QM: it's completely natural to be confused. Our brains simply didn't evolve to be able to visualize quantum effects. QM has nothing to do with consciousness, or "mental states" as you put it, so don't be thrown off by nonsense mysticism.

 

As far as learning goes, you'd probably appreciate the Feynman Lectures.

[Stratus]

ah, so what you're saying is that the sinusoidal electric and magnetic fields are the waves? and each peak of the fields is the peak of the waves? I think I understand that now.

 

I'm still slightly confused about the electrons jumping around though. since light is an EM wave ((I believe it is, correct?) , it should be created by the sinusoidal waves, but a few of my books say that light is created from the jumping electrons emitting photons? Or, is that only when it's being reflected?

 

Ah, thank you for the advice. I've been reading through past topics for the past few days and I was completely lost. I was just thinking I was very dense. I guess the more time you're studying QM though, the more you understand.

 

 

Thank you, I'll look the lectures up right now.

[Mike Smith Cosmos]

I'm still slightly confused about the electrons jumping around though. since light is an EM wave ((I believe it is, correct?) , it should be created by the sinusoidal waves, but a few of my books say that light is created from the jumping electrons emitting photons? Or, is that only when it's being reflected?

This Picture, not intended to be absolutely correct , is however one I produced to deal with the very moment of Electron Jump you ask about.

If you are anything like me , you need some form of image to hang ideas on . Some of the Mathematicians are able to contain the idea with just maths . Not me ! I must have an Image to hang more information on . Bit like a Spider Diagram or mind map. Hope this may be of some use in your visualisation.

 

Mike

 

 

 

The idea being , that the electron in the higher energy band ( mauve One ) attempts to fall to the lower energy band (red ) , but in so doing , has to shed a quantum of energy ( difference in Energy ,between the two bands or orbitals ) it does so by producing / or changing nature into a PHOTON of Radiation ( light , Electro Magnetic wave of some sort ) That is illustrated not to be taken too literally by the small and larger star haring off into the distance at vast light speed. ( exit left )

Edited May 6, 2013 by Mike Smith Cosmos

[swansont]

May I ask if this is normal for someone new to physics, or if I'm sure being really dense? Such as, I'm rather confused with quantum superpositions. I understand most everything about schrodinger's cat, but how is this useful in real life quantum physics? I mean, what causes things to be in a superposition? Is it more of a mental state, or is it something we can measure?

Yes we can measure it. Superposition is used in atomic clocks. By putting an electron in a superposition of two states, from a QM view it is oscillating between those states, i.e. the atom "ticks" at a frequency dictated by the energy difference between the states. Through some additional steps we can use this to count the number of oscillations and keep time.

 

What I mean by this is, how can we tell if something is in a superposition?

Systems in superpositions will interfere when interacting. You will get different answers for certain interactions if they are in a superposition vs in a definite state. But you really need to go through the math to see this, which requires learning some QM.

[Stratus]

This Picture, not intended to be absolutely correct , is however one I produced to deal with the very moment of Electron Jump you ask about.

If you are anything like me , you need some form of image to hang ideas on . Some of the Mathematicians are able to contain the idea with just maths . Not me ! I must have an Image to hang more information on . Bit like a Spider Diagram or mind map. Hope this may be of some use in your visualisation.

 

Mike

 

DSCF3299.JPG

 

 

The idea being , that the electron in the higher energy band ( mauve One ) attempts to fall to the lower energy band (red ) , but in so doing , has to shed a quantum of energy ( difference in Energy ,between the two bands or orbitals ) it does so by producing / or changing nature into a PHOTON of Radiation ( light , Electro Magnetic wave of some sort ) That is illustrated not to be taken too literally by the small and larger star haring off into the distance at vast light speed. ( exit left )

Thank you for the very nice visualization ((that is also a very nice portrait, much better than anything I could draw/paint)).

But, I actually understand the process pretty well. My question was that, I've heard that the perpendicular magnetic and electric field create EM waves, which are light. But, I've also heard that the electron movement creates photon, which are light. So, do both create light? Or am I misunderstanding something in my text books?

What i'm thinking right now is that the electron movement is only used to reflect light after the light that was created by the fields interacts with an object.

 

 

 

 

Yes we can measure it. Superposition is used in atomic clocks. By putting an electron in a superposition of two states, from a QM view it is oscillating between those states, i.e. the atom "ticks" at a frequency dictated by the energy difference between the states. Through some additional steps we can use this to count the number of oscillations and keep time.

 

 

Systems in superpositions will interfere when interacting. You will get different answers for certain interactions if they are in a superposition vs in a definite state. But you really need to go through the math to see this, which requires learning some QM.

ohhhh, I see. now I realize that I'm probably being a nuisance here asking so many questions, but I'm just very interested in this is all xD.

I believe that Schrodinger's cat is a thought experiment of superpositions, correct? But, based on Schrodinger's cat, once a superposition comes into contact with real matter (protons, air molecules, etc), nature breaks down to one position? So, my question is, how do we keep something in a superposition when it breaks down so rapidly according to the cat story? Or am I misunderstanding?

[swansont]

Thank you for the very nice visualization ((that is also a very nice portrait, much better than anything I could draw/paint)).

But, I actually understand the process pretty well. My question was that, I've heard that the perpendicular magnetic and electric field create EM waves, which are light. But, I've also heard that the electron movement creates photon, which are light. So, do both create light? Or am I misunderstanding something in my text books?

What i'm thinking right now is that the electron movement is only used to reflect light after the light that was created by the fields interacts with an object.

 

Motion of a charge creates a magnetic field, but it's the acceleration of a charge that creates photons; acceleration gives you a changing E and changing B field. You can also get photons from a transition between states of an atom or nucleus, or by annihilation of matter and antimatter.

 

 

ohhhh, I see. now I realize that I'm probably being a nuisance here asking so many questions, but I'm just very interested in this is all xD.

I believe that Schrodinger's cat is a thought experiment of superpositions, correct? But, based on Schrodinger's cat, once a superposition comes into contact with real matter (protons, air molecules, etc), nature breaks down to one position? So, my question is, how do we keep something in a superposition when it breaks down so rapidly according to the cat story? Or am I misunderstanding?

 

A superposition will be destroyed by an interaction that forces the system to be in an eigenstate. Complex systems generally de-cohere more readily than simple ones. Photon superpositions have been kept intact for distances of many tens of kilometers.

[Mike Smith Cosmos]

My question was that, I've heard that the perpendicular magnetic and electric field create EM waves, which are light.

But, I've also heard that the electron movement creates photon, which are light. So, do both create light? Or am I misunderstanding something in my text books?

 

 

Maxwell showed that by combining the formula for electric fields and magnetic fields a combined self propagating Electro-Magnetic field would be produced (E fields being at right angles to the M fields ) which would move at 300,000,000 meters per second . Light , had already been proved to travel at 300,000,000 meters per second . So he therefore said " Light must therefore be an Electro-Magnetic Wave. "

 

Max Planc (from Black Body radiation) and Einstein ( from the photo electric effect ) worked out that as Radiation came from atoms , particularly the electrons , in set sized Energy Chunks they named " Quanta" and " Photons " . Thus if we/they put the two together " A Photon is a very Precise piece of Electro -Magnetic Radiation ( which can be light, or radio waves, ) of a set , quantum sized chunk of Energy . ( there is a formula for this linking Energy E , Planks constant h and Frequency of the E-M wave f ) So when an electron jumps or is pushed in to or out of energy bands a set amount of energy is involved. Planks constant is a fixed figure/constant. So the frequency is SET by the formula. ( look it up on wikipedia under Plank or ask and I will give it to you, if you need it.

 

So really its all linked together. Is that enough or would you like a bit more of an explanation.

 

I'll let Swansont talk about superposition , that's his day job

 

OOPs ! He Already has. .He has overtaken my typing . Oh well you have a couple of perspectives !

Edited May 6, 2013 by Mike Smith Cosmos

[Stratus]

Okay, I think I understand now. If what I gathered it correct, then

 

A set amount of energy (Plank's constant I imagine?) is required to be released or absorbed for an electron to jump up or down through the levels. When an electron jumps down, it released a self propagating EM wave in the form of a photon? And with a certain wavelength, that photon would be light?

 

If this is not correct, maybe you could correct the step that was wrong?

I'm sorry about not understanding this perfectly, it's been a long day so far and I'm only in high school, so I might be a little dense at all this stuff xD.

[Mike Smith Cosmos]

Stratus, on 07 May 2013 - 00:12, said:

Okay, I think I understand now. If what I gathered it correct, then

 

A set amount of energy (Plank's constant I imagine?) is required to be released or absorbed for an electron to jump up or down through the levels. When an electron jumps down, it released a self propagating EM wave in the form of a photon? And with a certain wavelength, that photon would be light?

 

If this is not correct, maybe you could correct the step that was wrong?

 

I'm sorry about not understanding this perfectly, it's been a long day so far and I'm only in high school, so I might be a little dense at all this stuff xD.

This is the Quote from Wikipidia

 

Quote

" the Planck postulate, that electromagnetic energy could be emitted only in quantized form, in other words, the energy could only be a multiple of an elementary unit , where is Planck's constant, also known as Planck's action quantum (introduced already in 1899), and (the Greek letter nu, not the Roman letter v) is the frequency of the radiation. Note that the elementary units of energy discussed here are represented by and not simply by . Physicists now call these quanta photons, and a photon of frequency will have its own specific and unique energy. The amplitude of energy at that frequency is then a function of the number of photons of that frequency being produced per unit of time."

Interpreting this

 

The Chunk of Energy or quanta is not h ( Planks constant , but h multiplied by frequency f ( here they use v for frequency ) ( so many oscillations per Second ) Thus the chunk of Energy Quanta) is hxf

 

 

. [ Formula E = h x f joules ]

 

{ h units joules -seconds

f units ocsillations per seconds hertz

seconds cancel

left with joules of energy } ( a match flame is about 2000-4000 joules )

 

link http://www.en.wikipedia.org/wiki/Planck%27s_constant

 

 

.. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

. YELLOW/ ORANGE LIGHT

 

The Energy gap ( between two energy bands say in a sodium atom ) is set , fixed , all ways the same. In the Sun , in a sodium street light , in Salt . Always the same energy gap . So , when you cause the electron to Jump , or more often to return from a higher to a lower energy band (like my picture) .

 

Use the formula E is Fixed (band gap) h is certainly fixed at h = 6.62606957(29)×10⁻³⁴ j-s

 

thus frequency F =E/h = set value = Yellow/orange light (set , fixed)

 

--------------------------------------------------- --------------------------------------------------

 

That's why Sodium street lights are yellow/orange. That's why when you throw salt ( Sodium Chloride NaCl ) into a fire or flame it goes Yellow/orange . and Yellow/orange can be seen in Sunlight . ( last one is a bit more difficult )

 

 

 

 

Sunlight seen through a special spectroscope will see yellow/black sodium absorpbsion lines

. I I

. IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII

. I I

. 2 absorbption lines ( light being re absorbed in Suns' part sodium atmosphere )

. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

mike oops ! mike !

Edited May 7, 2013 by Mike Smith Cosmos

[Stratus]

Ahhh, I see. So, the chunk of energy (the band gap) in the quanta that is released is equal to P (Planck's constant) times F (the frequency). And, if you divide the energy (band gap) divided by planck's constant would give the frequency of the wavelength, or the color of the light ((assuming the wave is of visible light) ?
If this is correct could someone confirm it for me?

 

I, being very dense on this, still am slightly confused about the mechanics of how light come into existence though. From what I've been reading and placed together

 

Electron jumps releasing energy -> creates an electric field which creates a perpendicular magnetic field which continues through this cycle -> this energy moving at the speed of light is called a photon-> photon interacts with matter that is affected by the electromagnetic force, which causes the electrons in that atom to jump -> electron jumps back down releasing another photon, photon eventually reaches our eyes and we see the object.

 

Is this correct?

Thank you so much for your help everyone. I'm still very new at this whole thing so it's very hard to comprehend, but I'm trying to understand. I really am xD.

[Mike Smith Cosmos]

Ahhh, I see. So, the chunk of energy (the band gap) in the quanta that is released is equal to P (Planck's constant) times F (the frequency). And, if you divide the energy (band gap) divided by planck's constant would give the frequency of the wavelength, or the color of the light ((assuming the wave is of visible light) ?

If this is correct could someone confirm it for me?

 

I, being very dense on this, still am slightly confused about the mechanics of how light come into existence though. From what I've been reading and placed together

 

Electron jumps releasing energy -> creates an electric field which creates a perpendicular magnetic field which continues through this cycle -> this energy moving at the speed of light is called a photon-> photon interacts with matter that is affected by the electromagnetic force, which causes the electrons in that atom to jump -> electron jumps back down releasing another photon, photon eventually reaches our eyes and we see the object.

 

Is this correct?

 

Thank you so much for your help everyone. I'm still very new at this whole thing so it's very hard to comprehend, but I'm trying to understand. I really am xD.

 

You are not very far off the mark, if not spot on . I just need a little time . I will not say why but it begins with D and another D

 

Mike

Edited May 7, 2013 by Mike Smith Cosmos

[Stratus]

Alright, thank you for the help understanding this. ^^

[TJ.]

Light is created by an accelerated charge. Furthermore, photons (light) are the gauge bosons for the fundamental electromagnetic force. So technically all charged/magnetic particles/objects emit virtual photons that mediate the force of attraction or repulsion between two charged/magnetic particles.