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16 votes

Avoiding radar detection using active noise control instead of a stealth fuselage

To get an idea of the difficulties, we will consider a similar problem with sound. There are places with names like "Echo canyon". If you shout, the sound reflects of a nearby canyon wall ...
mmesser314's user avatar
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14 votes

Avoiding radar detection using active noise control instead of a stealth fuselage

The essential problem with that is that transmitting emits energy. You can cancel out the reflection in a particular direction this way, but in other directions it won't cancel. In effect, you're ...
John Doty's user avatar
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13 votes

Why is intensity additive?

In a similar question, the good answer https://physics.stackexchange.com/a/714653/219989 shows a calculation of how when you have N sound waves with identical frequency - but uniformly distributed ...
Nadav Har'El's user avatar
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12 votes

Treatment of infinite reflections in thin-film interference

You are quite correct that in general we need to consider multiple reflections. For example a Fabry-Pérot etalon relies upon multiple reflections to function properly. However in simple treatments of ...
John Rennie's user avatar
12 votes

Why interference is happening with two slits but diffraction is happening with one slit?

"Diffraction" and "interference" draw our attention to different aspects of the way waves propagate in space. Underlying both words is the same thing: just waves propagating. When ...
Andrew Steane's user avatar
11 votes

Avoiding radar detection using active noise control instead of a stealth fuselage

from https://doi.org/10.1109/WDDC.2007.4339412 Both answers are correct in explaining why cancelation is a bad scheme to avoid radar detection of an airplane. But repeating the incoming radar signal ...
hyportnex's user avatar
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11 votes

How come two electrons interfere?

In the double slit experiments, you never have two different electrons interacting. It is always the wavefunction of a single electron interfering with itself. You should not confuse the electron (...
Léo Vacher's user avatar
  • 1,115
9 votes

Why does gravity-induced quantum interference in quantum mechanics show that gravity is not purely geometric at the quantum level?

In page 131, it is said : Because the mass does not appear in the equation of a particle trajectory, gravity in classical mechanics is often said to be a purely geometric theory. Basically what it ...
Agnius Vasiliauskas's user avatar
8 votes

Treatment of infinite reflections in thin-film interference

As has been pointed out by @JohnRennie the Fabry–Pérot interferometer is a device which relies on significant multiple reflections between two parallel surface. However you will note that the ...
Farcher's user avatar
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8 votes

Double slit experiment with polychromatic light

Interference between different frequencies between the source and the screen doesn't matter because light propagation is linear. You can compute the fields at the screen for each frequency separately ...
benrg's user avatar
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7 votes

How do EM waves interact with one another?

A crucial characteristic of electromagnetic waves is that in everyday circumstances they can pass right through one another without any disturbance. This means that light sources from all the lit-up ...
niels nielsen's user avatar
7 votes
Accepted

Will the interference pattern still be observed with gamma rays in double slit experiment?

If you look at the table here of the wavelengths of electromagnetic waves you will see that gamma rays have very small wavelength,smaller than 10 pico meters. The smallest atom, the hydrogen atom has ...
anna v's user avatar
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7 votes

Double slit experiment with polychromatic light

It should not be ignored. Presence of multiple frequencies will definitely lead to blurring of the pattern. You can see that if you do the experiment with incandescent light instead of LED or laser ...
Jos Bergervoet's user avatar
7 votes

Why does classical physics not predict particles in the double-slit experiment to land in just two different locations?

You need to look first at the case with only one slit. There you will find that not just one spot is illuminated (straight behind the slit) but that you get diffraction [Fraunhofer diffraction ...
Jos Bergervoet's user avatar
6 votes
Accepted

Why does gravity-induced quantum interference in quantum mechanics show that gravity is not purely geometric at the quantum level?

Your text, in §2.7.2, 3rd ed, points out that the coupling to the gravitational potential in the Schrödinger equation, $$ \left (i{\hbar\over m} \partial_t + {\hbar^2\over 2m^2}\nabla^2 -\Phi_{grav}\...
Cosmas Zachos's user avatar
6 votes

Why is intensity additive?

The conceptual reason is that different sources have uncorrelated phases, so that at each frequency, they will randomly either add or subtract from the sound pressure. Adding these sources together is ...
Sten's user avatar
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6 votes
Accepted

Double slit experiment with polychromatic light

When talking about the Intensity of monochromatic light one usually argues with waves of the form $\exp(ik\rho)$, $\rho$ beeing the distance to the corresponding slit. Letting them interfere on a far ...
Zaph's user avatar
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5 votes

Does force change with wave function?

Electrons are elementary particles and as such, they are modeled with quantum mechanics, which the wave function obeys. To calculate the wavefunction one introduces the potentials that the electron is ...
anna v's user avatar
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4 votes
Accepted

Question on Babinet's principle example

You are too optimistic about the possibilities. With Babinet's principe you can only replace a mask by its inverse. So where it is transparent it becomes blocking and vice versa. If you have a mask ...
Jos Bergervoet's user avatar
4 votes

Why interference is happening with two slits but diffraction is happening with one slit?

Each slit spreads light out to produce what is called a diffraction pattern and the light from each of the diffraction patterns overlap which results in an interference pattern. Usually the separation ...
Farcher's user avatar
  • 96.8k
4 votes

Why does classical physics not predict particles in the double-slit experiment to land in just two different locations?

It is often said that particles are sometimes particles and sometimes waves. This is one source of confusion. They are sort of like particles and sort of like waves. They are really like nothing ...
mmesser314's user avatar
  • 39.5k
4 votes

Why does classical physics not predict particles in the double-slit experiment to land in just two different locations?

Why does classical physics not predict particles in the double-slit experiment to land in just two different locations? It does. If it’s a particle. Classical physics predicts that if you are firing ...
Dale M's user avatar
  • 337
3 votes
Accepted

Double slit experiment with detector and experimenter

Short answer: A) Interference pattern from two slits B) It depends on what you mean by "the results are deleted afterwards," but unless the information is destroyed in a very specific and ...
Punk_Physicist's user avatar
3 votes

Is my understanding of the double-slit experiment correct?

You're doing fine. People will quibble with some of your language choices. They will point out that your way of thinking is not as useful as some other ways of thinking for one or another specific ...
WillO's user avatar
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3 votes

What is the physical reasoning behind the mathematical derivation of double-slit interference pattern and single-slit diffraction pattern?

About "(...) the minima equation for double slit and single slit are opposite of each other, despite both are built on a similar concept." no one has answered yet. The answer to this ...
Radek D's user avatar
  • 105
3 votes

Does two same light bulbs produce light of same frequency?

Ordinary light bulbs emit photons of light with a wide range of frequencies and with random phases. To observe interference patterns you need either (a) a very small difference in path lengths (e.g. ...
gandalf61's user avatar
  • 55.5k
3 votes

How come two electrons interfere?

Electrons are just quanta of the electron field. To say there is one electron in an experiment means more or less the same as to say the number operator of that field has negligible probability to ...
alanf's user avatar
  • 8,066
3 votes

How come two electrons interfere?

Electrons would repel each other. If they overlap, they might not for very long. Electrons can overlap. They do so in an He atom. Both electrons occupy the lowest energy orbital. Being Fermions, they ...
mmesser314's user avatar
  • 39.5k
3 votes

Treatment of infinite reflections in thin-film interference

Thin film interference is typically used to create anti-reflection coatings. In this situation (unless the angles allow total internal reflection), there are not multiple reflections. The number of ...
Stevan V. Saban's user avatar
3 votes
Accepted

What is the upper limit of size for diffracting an object?

As far as I know the largest object that has been successfully diffracted is a oligoporphyrin molecule with a molecular weight of about $25000$. This was done on 2019 and is reported in Quantum ...
John Rennie's user avatar

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