# Tag Info

3

It needn't. Take a look at Snell's law, $$n_1 sin{i}=n_2 sin{r}$$ If you're sending a ray from an optically denser medium to a less denser one, $n_1 > n_2$. As you increase $i$, for some value, $n_1 sin{i}=n_2$ (since the sine function gives values always lesser than $1$). For that value of $i$, you find that $sin{r}=1 \implies r={\pi \over 2}$, which ...

-1

Essentially your question is what happens to light in a moving medium. In your case a rotating (I assume, isotropic) cube. The qualitative behavior is of course independent on the refractive index. Your slow light setting is appealing to imagine but qualitatively not different from a normal glass cube. Let me modify your experiment a bit. Assume a rod (so ...

0

Yes, you will alter the beam direction, but not by the same amount as you rotated the cube. The reason I think this is what happens is as follows. Light can interact with phonons ('quanta of movement in the material'). For example, acousto-optic modulators make explicit use of this coupling to change the direction of an incoming laser beam. They are often ...

0

The attempt looks like a guess. You should explain as much as you can about how you arrived at that answer. A hint would be that for maximum reflection, the reflected waves should all be in phase. For that to happen, the total in-and-back distance traveled in layer 1 should be an integral number of wavelengths. Likewise, the total in-and-back distance ...

0

The answer depends on the angle of the goggles with respect to the surface of the pool. What you say is true when the two are parallel, but you did not specify that. Otherwise the two water interfaces (with the air, and with the mask) will act like the (not parallel) faces of a prism, and the light will not return to the original direction inside the mask. ...

0

The dispersion is normally measured using the Abbe number, so you need to find a material with a low Abbe number. This diagram from Wikipedia shows Abbe numbers for a range of commercial glasses, though the materials tend to get rather esoteric at the low Abbe number end. Refractive index changes rapidly near optical absorption edges, so any material that ...

1

It is best to first simplify the situation and think about why is the frequency of the wave the same as the source. Considering the case of a string attached to an oscillator, if the frequency of the oscillator and the wave were different, there would need to be a discontinuity in the string. The fact that the string is attached to the oscillator means ...

0

See in Wikipedia the topic "Phase velocity" http://en.wikipedia.org/wiki/Phase_velocity . When the light passes from a less refractive medium to one more refractive one, e.g. from air into water, the phase velocity is changed without changing its frequency. In short, consider a plane wave hitting the water surface. Let's think for simplicity in two ...

1

A nice analogy that will hopefully help you to understand this, is to imagine the wavefront as a marching band. They all walk shoulder to shoulder, and the line is one person thick. Imagine the air as land they walk over, and the material as a beach. Their walking speed on firm soil is faster than on the beach sand. When they approach the beach under an ...

0

Just to make everyone else know the answer: the angle i is the one from the continuous line to the perpendicular, clockwise

1

This is not a complete answer, just a possible way to handle the problem. I assume that the transversal section of your prism is a triangle with all the angles equal to 60⁰. Let's denote by A, B, C, the three corners of this triangle. Let's denote by P_1 the point of incidence on the prism, and then by P_2, P_3, P_4 the points where the ray falls on the ...

2

It depends on how accurately you want to measure the refractive index. The refractive index typically only changes by about 1% over the visible spectrum so if you're happy with that accuracy just go ahead and estimate the central point of the refracted ray. As Floris suggests, you could try and judge the refraction angle separately for the different colours ...

4

Of course you can. The prism is likely to disperse the light - that is, different colors will be refracted by different amounts. That means you don't just get "a" refractive index, but with careful experimental setup you will get the entire refractive index curve: a different value for every wavelength / color. Setup: a narrow beam of white light incident ...

2

Perhaps you're looking for a beam expander? It takes a collimated beam and expands or reduces its size. I make no claim as to whether it reduces the intensity to a "safe" level, but it certainly reduces intensity.

2

The answer is YES. See diagram: The key here is that you can write down the expressions for the angles $a_2, a_3, a_4$ in terms of the angles of the prism $\alpha, \beta, \gamma$ and the first angle $a_1$. Now $\alpha + \beta + \gamma = 180$ and you know you must have total internal reflection with the first three angles, but not with $a_4$. $$a_2 = ... 1 Here is the bookwork answer. Consider the boundary between two media. Draw a rectangular loop of side \delta x and \delta y. Have an E-field either side of the boundary that is parallel to the boundary. The E-field is E_1 in medium 1 and E_2 in medium 2. Now use the integral form of Faraday's law.$$ \oint {\bf E} \cdot d{\bf l} = - \int ...

0

Refractive index manifestly plays a role in Mie scattering: if the suspended colloids have the same refractive indexand characteristic impedance as the surrounding fluid, the whole system is electromagnetically homogeneous, and there is no scattering. For nonmagnetic materials, this statement is the same as that of a homogeneous refractive index. So I ...

Top 50 recent answers are included