# Questions tagged [wave-particle-duality]

Use this tag for questions relating to the "wave-nature of particles" or the "particle-nature of waves" as they are often discussed in quantum mechanics, where a single object has properties of both classical particles and classical waves.

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### Failure of Newton's corpuscular theory and success of photon theory of light

Corpuscular theory of light States that: Light is made up of small discrete particles called "corpuscles" (little particles) which travel in a straight line with a finite velocity. ...
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### If particles are also waves cant we invert them by making it reflect off a fixed boundary?

When a pulse on a rope gets reflected off a fixed boundary, it phase shifts 180° and inverts itselfs. If particles are also waves, will doing an equivalent thing create antiparticles? Is it possible ...
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### Difference between de Broglie wavelength and electromagnetic wavelength?

So we have to find the ratio of wavelength of electrons in 1st and 4th orbit of an atom. Why do we have to use de Broglie wavelength and not $E = \frac{h c}{\lambda}$ ?
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### How can an electron be a point particle but also a wavefunction?

A point particle is a point in space of a fixed co-ordinate. However, the wavefunction must always be spread out in space to be normalizable to unity.
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### Energy of light across different media

As a high school student, I was studying the dual nature of matter and radiation and wave optics. According to Planck's theory, the energy of a particle is given as hf where h is the Planck constant ...
1 vote
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### Why is a relativistic calculation needed unless $pc$ is much smaller than the rest energy of a particle?

After introducing the de Broglie wavelength equation, my textbook gives a rather simple example where it asks to find the kinetic energy of a proton whose de Broglie wavelength is 1 fm. In the ...
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### Does a wave function not collapse upon detection?

In Sabine Hossenfelder’s YouTube video “The Delayed Choice Quantum Eraser, Debunked”, she states that even if you detect which slit the wave function goes through (in the double-slit experiment) then ...
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### Why exactly can we not know the position and momentum of a given particle?

I have heard that this is to do with the fact that a particle is also a wave. However, I do not understand why this would cause this. Surely, you could use the formula used for finding the velocity, ...
1 vote
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### What defines an 'object' with regards to particle-wave duality?

If any object, such as a ball, can exhibit wave behavior, I am confused about how such an object is defined. Does a ball itself have a wavelength? Does every single atom that composes it have a ...
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### Observer effect in quantum world

Why do the observer effect happens? Why do when seen a photon becomes a particle and when not seen shows wave nature? And why does not it happen on macroscopic level?
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### In the de-broglie's model of atom, what he said about the path of electrons?

I saw animations in which electron is revolving around the nucleus in a sinusoidal wave like path. And I saw animation in which a standing wave is shown (no electron) So what actually de-broglie ...
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### What is exactly mean by wavelength in De Broglie equation?

I'm wondering what exactly is meant by the wavelength in De Broglie formula $p=\frac{h}{\lambda}$, where $p$ is the momentum of a particle and $\lambda$ is the wavelength. I know that a wave function ...
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### What exactly is wave particle duality? [duplicate]

I am a 12th grade student I want to clarify some fundamentals about waves.It's clear to me when some one says sound propagates As a wave(the variations of air densities as a function of distance from ...
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### Quantum theory - How a particle functions as a wave without a medium? [closed]

I would love to understand, what does it mean that each particle also functions like a wave, after all even when sending a single particle it creates an indentation. How does a single particle in ...
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### Photoelectric effect and wave nature of light [duplicate]

We know that when a light of specific frequency is collided on the silicon metal plate electron released from it, this is the photoelectric effect This effect proves the particle nature of light , but ...
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### What is causing the diffraction pattern on my ceiling?

When I wake up in the morning and look at my curtains, I see a pattern on the ceiling made by the light going through the gap between my curtains. I have added a picture of it below. I remember from ...
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### Is my understanding of the double-slit experiment correct?

I'm no quantum scientist. I'm just a software engineer with a healthy (?) fascination with quantum mechanics and knowledge gained from Googling. :) I've read many different articles about the double-...
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### Can molecules used in double slit experiments interact with light? [closed]

If a photon hits a molecule while it's in a wave state will it collapse it into a particle?
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### Can we calculate energy of light using wave theory? And will it be the same as $E=h\nu$?

From wave theory we got that energy of wave is given by $E = \frac{1}{2} \epsilon |\vec{E}|^2$ and from particle theory $E=h\nu$. So can we use wave theory to calculate energy of wave?
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### Lack of Momentum exchange between photons upon apparent coalition

When two light beams made up of photons collide, say at an angle, in the same plane, they do not impart any momentum to the photons in each other. But, momentum is imparted by the same photons on ...
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### If quantum particles are always waves, then what are we really measuring the position, angular momentum, spin etc. of?

I've been losing sleep trying to marry, in the usual QM formulation we've been learning, what my lecturer said in our problems class a few weeks back - 'quantum particles are never particles (in the ...
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### De Broglie's relation under gravitational force

Does gravitational force affect the wavelength produced due to movement of an object?
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### Particle associated with material waves according to Wave particle duality

What would be the particle associated with the material waves (like water waves, sound waves) according to Wave particle duality and de Broglie hypothesis? Are those the medium particles (or ...
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### In what physics scenarios is it appropriate to consider an electron a ball, vs. a cloud, vs. a probability distribution?

These articles says the electron is a near perfect sphere: https://futurism.com/electron-edm-experiment So, what is our intuitive answer to the question? In all artists’ impressions of the atom, we ...
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### Had scientists ever fired single protons/electrons/particles before Einstein's work on the photoelectric effect?

Had scientists ever managed to fire/detect single, individual particles, photons/electrons/etc., before the photoelectric effect was discovered and Einstein's work on it saying that light also acted ...
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### Is a conservation/symmetry law behind wave-particle duality?

Please help me in solving a question stuck in my head about symmetry and conservation laws? Can wave-particle duality be considered an atomic-particle symmetry? And if so, what is the conservation law ...
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### Are photons and electrons "elastic" particles?

My teacher told me that Photons are elastic particles (allegedly it was a postulate of Max Plancks's Quantum theory too) and that during the photoelectric effect due to "elastic collision" ...
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### Why is there no time delay in photo electric effect? [closed]

Can someone explain to me (in simple words) why there is no time delay between photon absorption and photoelectric emission?
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### How to reconcile diffraction with the Heisenberg Uncertainty Principle?

When a particle of momentum $p$ (say $10^{-23}$ kg m/s e.g. an electron moving at 10 000 km/s) falls on a slit and passes through, what is its momentum after the slit? (One can also have a flux of ...
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### Does the quantum nature of light arise from its interaction with matter? [closed]

I have a desire to reconcile the results of the photoelectric effect with the Maxwellian picture of electromagnetic radiation. I wish to explore, the possibility that the quantum nature of the photon ...
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### Quantum Mechanical Interpretation of Rutherford Experiment

Ernest Rutherford performed the gold foil experiment; alpha particles were fired at a gold foil and the alpha particles were scattered. This result disproved Thomson's plum pudding model of atoms. ...
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### How does wave-particle duality explain the interference pattern? [closed]

The screen is the Y axis and the line perpendicular to it is the X axis. We fire an electron with a well-defined momentum $p_x$ in the X direction. Shouldn't the x-co-ordinate of the particle follow a ...
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### Particle- and wave-like properties

Is wave-particle duality a real concept or a pedagogical tool? In a less opinion-based way: what are particle properties and wave properties of a particle (that we speak of particle properties of ...
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1 vote
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### Why the photomultiplier experiment proves that photon is a particle, not a wave?

In QED Feynman describes the photomultiplier experiment as a proof that a photon behaves as a particle. The logic is as follows: with monochromatic single photon light source a photomultiplier coupled ...
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### Behavior of electron in free state and bound state

Why does a free state electron totally behave like a particle? also what will be the behavior of electrons in bound state?
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### Do we not know that momentum is certainly not conserved at single electron double slit experiments?

I am aware that tons of experiments are performed on this topic and the scientists try to be very careful with the experiments and take every possibility into account. In a single electron double slit ...
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### Comparing momentum of electron and photon and the correct usage of electron volt

I was trying to solve this question where we had a photon and an electron with the same energy $E$, and we were asked to compare their momentum. I know, for photons we have $E=p_{\gamma}c$ and for ...
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### How is Bragg Scattering an example of light behaving as a particle?

I am a student at the University of Michigan and this semester I am taking Modern Physics as part of my Physics minor. In a lecture on Wednesday my Prof. mentioned that Bragg Scattering is one of many ...
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### Does Wave-Particle Duality Mean "Particles" are Just Waves With Short Wavelengths?

I have the following question about wave-particle duality: Are particles really just waves with short wavelengths? If this is correct, would it then be accurate to say: "everything in the ...
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### Does a particle interact with walls of a slit?

It is kind of mystical that a particle goes through a slit and eventually changes its impulse due to Heisenberg uncertainty. Since the slit is an opening, it must not have interacted with it. Does it ...
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### Where is a photon in space relative to the wave?

In electromagnetics you learn that an electromagnetic wave is a perturbation of the electric and magnetic fields that propagate in space according to the wave equation. This makes sense when you are ...
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1 vote
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### The difference between two formulas for wavelength [closed]

What is the difference between these formulas - \begin{array}{l} \lambda=\frac{h c}{E} \\ \text { and, } \lambda=\frac{h}{\sqrt{2 m k}} \end{array} There is a question - Question: The debroglie ...
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### Can particles be in a superposition of times as well as positions?

We often talk about the various possible positions a particle can have upon measurement according to the probability density. But owing to the profound link of space and time in relativity, why do you ...
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### Electron emission and photoelectric effect affected by intensity

It is said that when visible light is directed onto a metal surface, it doesn't emit electrons from the surface because intensity doesn't affect it. However, then it is said (relating to the equation) ...
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### Why do classical laws fail at small scales?(Heisenberg's Uncertainty Principle) [closed]

So I came across a question in my textbook: Explain why we can not apply classical laws to very small scales, but we can to large scales: a. using the de Broglie wavelength of matter. b. using ...
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### Photon as a wave

As I was writing tutorials for a new course in waves. Then I thought about a question - is a photon a standing or a travelling wave? I am not sure this question is well defined at all, so let me put ...
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### Microscope and dual nature of light

Does a light microscope also prove the particle nature of light? As in electron microscope there is either transmission or absorbance of electrons to create an image, hence the question above!
1 vote
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### Is there a hard clear division between a particle and a wave? [duplicate]

My limited understand is that photons can we both or is a particle and a wave. But they have 0 weight(?) I found this quote today: "Quarks, like all elementary particles, are excitations of a ...
1 vote