# Tag Info

5

This is going to be really hard to do with LEDs since they're not collimated. If they were instead lasers then you would have some options at your disposal. If you have control over the polarization then you can combine the beams using polarizing beam splitters with lower power loss (but you would have differently polarized light at the output, may or may ...

4

Suppose an EM wave is emitted by some source in a step fashion. That is, ideally, prior to some time $t_0$ there is no emitted wave, and after that time there is an emitted wave with some constant non-zero amplitude. An initial wave will leave the emitter at the speed of light in a vacuum, even if the light is passing through matter. This initial "front&...

2

An ideal lens takes a point source that is located on its focal plane, say $\mathcal {F}$ emitting monochromatic homocentric rays/spherical waves and transforms them into parallel rays/plane waves whose direction (propagation phase) depends on the location of the point source in the focal plane relative to the symmetry axis. By reciprocity it also goes the ...

2

Assuming everything is correct, and this red light is not a reflection of some other light source or something: one possible way of achieving this is that the medium is absorbing green light and emitting the red light through photoluminescence. So in this case it's technically not light changing frequency in the medium; it's "new" light produced by ...

2

I don't have Feynman's lectures available, but I am not sure if you have interpreted him correctly. The fact that the speed of light is different in matter (and varies with wavelength) is the foundation for such profound effects as refraction and dispersion. Just take any prism and see the effects, and you'll know that the speed of light in matter is real.

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If your system is equivalent to a single lens with focal lenght $f$, then you can proceed like if you had one only lens with that $f$, so $M_L=\frac{s'}{s}$, with $s$ the distance to the object

1

Two things you might want to do: your data aren't perfect, in particular, there are two vertical jumps in them, one at approx -2.6 and another at approx 1.5 (not sure if this is what you refer to as "dead time"). These vertical jumps are in fact phase jumps of your oscillations. You won't be able to fit the entire data set with a $\cos^2$ function ...

1

You only see the color that aims at you. From the higher drops that is red. From the lower drops that is violet.

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If the beam splitter is a non-polarising device and the setup is ideal, then statistically 50% of the photons go in one direction and 50% in the other. But this does not mean that at any point in time the ratio is 2:2. All other scenarios - with lower probability - are possible: 4:0, 3:1, 1:3 and 0:4.

1

To do this efficiently, you want an optical device known as an X-cube. This is a cube that has three input faces: for red, green, blue. The output face combines all of those. Look up "X-cube optics" on the web, (so you don't get X-cube toys). Since you also want a fourth channel, that is a complication. People would typically add a dichroic plate ...

1

How can an experiment built on the premise that light actually slows down in matter work, when light actually travels through the apparatus at the speed of light in a vacuum and only the phase-velocity of the superposed wave is lowered? Indeed. The correct functioning of the experiment is certainly good evidence supporting the premise upon which the ...

1

A metal is reflective because it is conductive. Conductivity will limit reflectivity as it gets thin and narrow. There are considerations beyond this of course if you want to make a solar sail. A metal wire mesh as thin as possible would be weak and fragile. Strength matters. Manufacturability of giant a sail matters. Ability to survive Earth's atmosphere ...

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Notation in Figure-01 : \begin{align} n_1,n_2 & \boldsymbol{=} \texttt{indices of refraction} \nonumber\\ \theta_1,\theta_2 & \boldsymbol{=} \texttt{angles of incidence and transmission} \nonumber\\ \mathbf i & \boldsymbol{=} \texttt{unit vector on incident ray} \nonumber\\ \mathbf t & \boldsymbol{=} \texttt{unit vector ...

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