Difference between particle and wave nature and black body radiation

Discussion in 'Chemistry' started by ash64449, May 25, 2013.

1. ash64449Registered Senior Member

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Hello friends,

i have a big trouble because i am not able to understand what is meant by particle nature and what is meant by wave nature.

I need to know what kind of behavior we classify it as wave nature and which behavior we classify as it to be particle nature?

Once you have explained it to me,difference in behavior of wave nature and particle nature,explain me what should be the experimental results if radiation were to act like a wave and then as a particle.

Obviously,the behavior would be of particle nature and as result Quantum Theory came in!!!

Well,i will tell you how much i know about black-body radiation and all its experiment.

An Ideal Body which absorbs and emits all frequencies of radiation is called a black-body and it's emitted radiation is called black-body radiation.

While observing a graph which has intensity at one axis and wavelength at the other,at a constant temperature,it is observed that intensity of the emitted radiation is greater as wavelength decreases,reaches a maximum value for a specific wavelength and intensity of radiation decreases with further decrease in wavelength.

I think according to wave nature of electromagnetic theory, i think( i am not sure,just a guess) as the temperature of black-body increases,frequency of emitted radiation increases but intensity of the radiation should be same as the intensity of the radiation through which we made the black-body to absorb.

But the result is that intensity is the function of wavelength at the constant temperature.

So how is this can be explained with particle nature? I think this is what helps to distinguish particle nature with wave nature.

3. wellwisherBannedBanned

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One analogy that helps you visualize particles and waves is to consider a boat moving on the water. The boat will create a wake, which are the waves the boat will make. The old ether theories have the particles making a wake in the ether analogous to the boat on water.

Say we had a second boat going in the opposite direction also making a wake/waves. The boats are analogous to two particles. If they have a head on collision they will both get destroyed because particles can't occupy the same space at the same time. But their wake/waves can overlap and add and subtract. The overlap the wakes makes a new composite wave that might look like one big boat but the two boats as particles can never add and subtract that way since overlap means disruption.

In the two slit experiment, a single photon can appear to send out waves that go through both slits at the same time.The particle/boat does not do this, since it can't be in two places at the same time. But its spreading wake/waves can travel through both.

The wave functions that define orbitals are connected to the wake/waves that the electron particles create. The particles/electrons cannot overlap in space, but their wakes can add and will try to minimize energy. If we minimize the wave energy then that means the particles need to be in certain places, which works out for the particles.

Say we had a wave tank with two waves generators, one at each side. The two wave sources are out of phase by 180 degrees, so they add in the middle where they cancel. What you would see is energy being generated from both sides, but silence in the middle of the tank due to the waves canceling. It is almost like energy is disappearing into a void.

The conservation of energy says the energy cant be created or destroyed, so it is hidden due to wave cancellation; dark energy. This is not another dimension of space, but is simply wave cancellation. Particles can't hide this way, since particles do not add and subtract like waves. The particles are still there, but they lack the visible wave expression.

If we take a partition, like a flat board and put it in the silence in the middle of the tank, we can cause the hidden wave energy to appear as the waves rise up out of the stillness. All this does is alter wave addition by adding a partition function.

In physics, when paired particles appear out of the void of space, this is due to a partition in the wave stillness; middle of our wave tank. What we see are the waves appearing, which are what we typically measure. We then infer particles. But the particles were already there, but without waves. Science is not used to particles without waves, so they assume it just appear when the waves appear, since we are biased for waves; wavelength/frequency.

5. ash64449Registered Senior Member

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Can you explain in terms of black-body radiation? That is can you explain difference in particle nature and wave nature by saying what would the experiment should be if radiation was a wave?

7. originIn a democracy you deserve the leaders you elect.Valued Senior Member

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Blackbody radiation is not going to give you much insight into the wave parictle duality of light.

8. TrippyALEA IACTA ESTStaff Member

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The photoelectric effect is an example of the particle aspect of the Photon. You shine a light on a piece of metal, and electrons are dislodged. If light was purely a classical wave, the energy of the electrons would be proportional to the amplitude of the wave, but that's not what we observe. What we observe instead is that the energy of the electrons dislodged is proportional to the momentum of the photon. This is the behaviour of a classical particle - unless you put spin on it, the harder you hit the cue ball, the faster the billiard ball it hits will move.

The double slit experiment, on the other hand, is an example of the wave aspect of the photon. In the double slit experiment, a photon behaves exactly the same as a classical wave does, you can see the exact same patterns in a tank of water.

9. IncogNegroBannedBanned

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Naturally "it" is not a particle or a wave. "It" is only what it is. It is the only thing that moves like it does; which is why we call it "it".
But when we talk we can say its field lines; reference something large

its frequency; reference itself

its energy; reference its surroundings

its momentum; reference mass

its spin; reference spin

Then maybe promote a good quality....

just seems like a good reference when talking about things and switching from astronomical to subatomic in my book atleast...

10. ash64449Registered Senior Member

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Why not? My textbook uses Black body radiation to explain particle nature of electromagnetic radiation.

11. ash64449Registered Senior Member

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Thank you! My Textbook too explains photoelectric effect.. I think i can understand them. But is it hard to understand the particle nature of electromagnetic radiation through black body radiation?

12. ash64449Registered Senior Member

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Sorry,i didn't quite understand your point.

13. TrippyALEA IACTA ESTStaff Member

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In classical mechanics, the equipartition theorem states thatthe available energy will be distributed amongst an objects vibrational modes. Think about a solid object for example. Let's say we have a 1 cm[sup]3[/sup] block of steel sitting on our desk. The equipartition theorem tells us that the thermal energy present in that cube is distributed evenly across all the vibrational modes available to the atoms in that cube. It doesn't glow white hot or freezing cold at room temperature, because those atoms that are moving very fast bump into other atoms frequently and loose energy; and those atoms that are moving very slow get jostled by faster moving atoms. The net result is we wind up with a statistical distribution of particle energies with an average value - the temperature of the cube.

We know that hot objects emit light, but when we first tried to describe the distribution of the frequencies, we tried applying the equipartition theorem to it. The problem with this is that when we applied it to a series of standing waves - IE when we tried to treat light as a classical wave, we found that the equipartition theorem predicted an infinite amount of energy emitted at short wave lengths. This problem became known as the Ultra Violet Catastrophy.

Planck's breakthrough was to realize that the frequency of the photon emitted by an oscilator was dependent on the frequency of the oscillator. In essence, the momentum of the photon is proportional to the momentum of the emitter.

So by treating a photon as a classical wave, we make predictions that we do not observe (the ultra violet catastrophe[/quote]), but, by treating a photon as a classical particle whose momentum is proportional to the momentum of the emitter, we can then correctly model a thermal continuum spectrum.

At least, that's my understanding anyway.

14. IncogNegroBannedBanned

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You can equip yourself with being better understood by using key words to denote behaviors observed within a system.

15. araucaBannedBanned

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I would look as the shorter the eave length you get more particles per unit of time if you compare to a wave length of one cm. the same as your wave length decrease again comparing to one cm. wave length you get more particles and in case by looking into electron configuration on an atom . if it incoming a photon will move the electron let say from 3s to 3p and if there are not more photon at the same frequency to maintain the electron at the 3p then the electron will fall back and will dissipate the incomed energy from the photon . So thinking in this manner I can see the photon as a particle and the frequency of the traveling photon in a given time.

16. arfa branecall me arfValued Senior Member

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Be careful about mixing together concepts like "intensity" and "temperature" when you want to know more about the particle and wave concepts used in quantum mechanics.

Since blackbody radiation can be described (i.e. plotted) using the first two terms, but against the "wave mode", not the "particle mode" of radiation. For instance as intensity against wavelength.
Ok, where does a particle with a wavelength fit in the radiation model? That's where QM is useful.

17. ash64449Registered Senior Member

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How did this solve the Ultraviolet Catastrophy?

18. TrippyALEA IACTA ESTStaff Member

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Because Planck's oscillators behave in the same way that atoms in a block of steel do. Those with very high energy lost it (or some of it) those with very low energy tend to gain it. From what I recall, the idea is that the oscillators are continuing abosrbing and emitting photons, which has the same net averaging effect that occurs in a block of steel. Essentially, the further above the peak (or average) the photons energy, the fewer oscillators there are capable of reaching that energy, thus avoiding the ultraviolet catastrophe.

19. IncogNegroBannedBanned

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Ultraviolet catastrophe... sounds like a bad movie.

20. exchemistValued Senior Member

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Yes. The key point, as I recall, is that Planck's formulation is equivalent to saying that the oscillators can only have certain set energy levels, rather than any amount of energy they like. Consequently, they must absorb fixed amounts (quanta) of energy to "jump" from a lower level to a higher, and similarly emit fixed fixed amounts when they drop back. This results in the distribution you describe, because it is less probable for an oscillator to accumulate many quanta than to accumulate only a few. Hence the higher energy levels are less populated than the lower ones.

21. araucaBannedBanned

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Are you guys brushing up on you chemistry books ?

The Planck Postulate was introduced by Max Planck in his derivation of his law of black body radiation in 1900. This assumption allowed Planck to derive a formula for the entire spectrum of the radiation emitted by a black body. Planck was unable to justify this assumption based on classical physics; he considered quantization as being purely a mathematical trick, rather than (as we now know) a fundamental change in our understanding of the world.[1]

In 1905 in one of his three most important papers, Albert Einstein adapted the Planck postulate to explain the photoelectric effect, but Einstein proposed that the energy of photons themselves was quantized, and that quantization was not merely a feature of microscopic oscillators. Planck's postulate was further applied to understanding the Compton effect, and was applied by Niels Bohr to explain the emission spectrum of the hydrogen atom and derive the correct value of the Rydberg constant.

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