New answers tagged

1

It can use both. One of the benefits of the Littrow configuration is that it does not cause astigmatism in the diffracted optical beam. (I think it also gives you the maximum spreading of the wavelengths, but I'm not sure now.) Therefore, although the Littrow configuration is defined as having the incident angle so that the light would come straight back ...


1

The light diffracted from a CD spreads very rapidly. If you can illuminate the CD using a very small light source that it at a white wall, with the CD a couple of feet away from a white wall, it should form a circular rainbow on the wall. It will be important to prevent any light from the source from hitting the wall directly: the white wall should appear ...


1

We are using a far field approximation. Each groove in the diffraction grating acts a source of circular waves and it's true that the distances from each groove to the central maximum are different. But once you get far enough away from the grating these differences in path length become much less than the wavelength of light. So while light from each ...


1

The reason is that all colors are in phase there. The so called zero order maxima concide and their sum produces white light.


1

I am not sure if I am using the same geometry as you. This is my best guess. Here are a couple images from https://sites.google.com/a/perthgrammar.co.uk/physics/courses/higher/particles-and-waves/35-interference-and-diffraction/353-diffraction-of-waves This is using a laser with a single wavelength. The important thing is it has a maximum in the center. ...


0

I think the author is trying to ensure that there are enough photons from many angles in order for the Huygens "interference" explanation to work. Water waves are made of many atoms and behave en masse, photons behave as individuals and many DS experiments actually use single photons! With single photons the pattern still emerges which questions ...


0

There is not enough context to fully interpret the quote. However, the statement appears to be incorrect or misleading. Edit 6/26/20: There is some ambiguity in the meaning of "source". If a laser beam is spread out to a diameter of 1 foot, then passed through a diffuser, what is the source? Is it the original laser beam, or is it the 1 foot ...


0

A reflection grating is not a mirror. It is an array of reflective grooves in a surface. Light reflected from the bottoms of the grooves is delayed relative to light reflected from the tops of the grooves, just as light transmitted through optically thick portions of a transmission phase grating is delayed relative to light transmitted through the ...


0

The time-independent Schrödinger equation within a constant potential (zero, for convenience) is the Helmholtz equation: $$\nabla^2\psi+k^2\psi=0$$ where $k=\frac{\sqrt{2mE}}{\hbar}$ and $E$ is the electron energy. This is the same equation that monochromatic radiation obeys: $$\nabla^2\vec{E}+k^2\vec{E}=0$$ where $k=\omega\sqrt{\mu \epsilon}$ is the wave ...


15

A realistic double-slit has two effects at play: there is single-slit diffraction from each sit (giving rise to the larger envelope) and there is interference between the two beams of light from each slit (giving rise to the smaller fringes). Some sources take into account both effects, but some sources ignore the single-slit diffraction effects and simplify ...


6

They are the same thing. The broader envelope in the interference pattern is a result of the diffraction in each slit, while the more rapid oscillations result from the interference of waves from the two slits. When the slit width is much smaller than the spacing of the slits, the envelope becomes so wide that it is essentially flat, so you get the second ...


-2

The first plot shows a two slit interference pattern, of any type of particle, atom or molecule. For the second plot I have no idea.


0

The explanations given so far did not match what the author wanted. The reason why the author asked this specifically is 'cos the even number of point sources was the foundation to deriving eventually the destructive interference pattern, which is w x sin(theta) = m x lambda. The correct explanation is that it need to be even number 'cos this is the only ...


0

If you're using an energy detector, it isn't either/or. The energy (Poynting) flux determines the intensity pattern on the detector. Electromagnetic interference determines the pattern in the Poynting flux. To calculate the pattern in the plane wave approximation, you may take the Poynting flux as proportional to the square of the electric field magnitude. ...


0

The diffraction pattern observed in the photos is due the power distribution in the light's EM field. The power density is proportional to the square of the amplitude of the E field. So it may be more appropriate to say that the diffraction pattern is created by variations in the square of the E field.


2

I think that we can use the model of the work done by a plane wave (even if for Fresnel difraction the waves are not treated as planes) to get the conclusion that the physical effects comes form the E-field: The work done in a charge of the screen depends on the Lorentz forces and its displacement: $$\Delta W = q(\mathbf E + \mathbf v \times \mathbf B).\...


6

It is the electric field. Whilst you may have two electromagnetic waves where $\vec{N}_1 = \vec{E}_1 \times \vec{H}_1$ and $\vec{N}_2 = \vec{E}_2 \times \vec{H}_2$, it is not necessarily true that $\vec{N}_{\rm tot} = \vec{N}_1 + \vec{N}_2$. Instead you should write $$\vec{N}_{\rm tot} = (\vec{E}_1 + \vec{E}_2) \times (\vec{H}_1 + \vec{H}_2)$$ because it is ...


2

Something has to detect the radiation. It could be a detector, or it could be light reflected from the screen into your eye. Whatever it is, the predominant mechanism for light to interact with matter is electrical. It could be absorption in a CCD pixel, or reflection due to induced electric dipoles, but in any case electric dipole intereactions are ...


3

The underlying level of reality is at present modeled by quantum mechanics. In this diffraction pattern built one photon at a time, it is the energy carried by the photons that creates the pattern: Single-photon camera recording of photons from a double slit illuminated by very weak laser light. Left to right: single frame, superposition of 200, 1’000, and ...


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