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Questions tagged [refraction]

Change in the direction of propagation of a wave when its transmitting medium changes.

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1answer
675 views

Equations of Fermat's principle/Snell's law in a gradient lens (sugar aquarium)

I'm trying to animate a beam of light inside a substance with gradient index of refraction as a function of y. A good example of that is a syrup inside an aquarium like here https://www.youtube.com/...
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2answers
86 views

Are there any real-world examples of refraction of light by magnetic permeability?

The question Fresnel Transmission Coefficient for Magnetic Field is interesting. Thinking about it led me to reflect upon what little I know of the history of optics, with refraction by lenses and ...
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1answer
72 views

Why does a rainbow only form with a 42° angle? [duplicate]

Why do rainbows only form with a 42° angle? Is there something special about this angle?
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1answer
26 views

Dielectric constant change in the atmosphere?

I'm curious about the refractive index changing in the atmosphere. As I understand it (and I may very well be wrong/naive) when a ray of light enters from one medium into another, the electric field ...
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1answer
245 views

What do individual rainbow-forming droplets look like?

Suppose we took a photo of a rainbow, but in such a huge resolution and sharp focus as to be able to see each droplet in good detail. What would the droplets look like? Would they be nearly uniformly ...
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1answer
280 views

Phase shift for reflection and transmission on absorptive medium with complex refractive index

I am trying to come with a hand-waving explanation as to why the reflection and transmission peaks of a metal-coated Fabry-Perot cavity are shifted in frequency (see the paper by Monzon & al). ...
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1answer
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Lensmaker's equation for thick lens in two different media

I've been looking around and I've found the lensmaker's equation for thick lens to be $$\frac{1}{f} = \frac{n_{lens} - n_{m}}{n_m} \big( \frac{1}{R_1} - \frac{1}{R_2} + \frac{n_{lens} - n_m}{n_m} \...
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2answers
38 views

Do mirages really occur due to total internal reflection?

Mirages occur in areas such as deserts due to difference in the refractive indices of layers of air. As the light ray travels from denser to rarer layers of air, slowly bending, it approaches the ...
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1answer
42 views

Path of sound in ocean where sound speed varies linearly with depth

In an ocean, described with $x-y$ Cartesian coordinates where $y=0$ on the sea bed, the sound speed varies linearly with $y$: $$v(y)=c+by$$ A textbook says that, if sound wave is emitted on the sea ...
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1answer
111 views

How is light trajectory affected by the trajectory of environment it passes through?

There's a sci-fi concept of slow light that I find very amazing: Imagine a glass material that has index of refraction $n$ say, $3,000,000,000$ which means: $$v_{glass} = \frac{c_{vacuum}}{n} = 0....
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0answers
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Thickness and refractive index of silica gel layer between fused silica and water interface

I learned that when fused silica contact with water, a layer of silica gel will be formed. However, I cannot find any reference about the thickness and the refractive index of the silica gel. Can ...
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1answer
196 views

Critical angle equations - air and not air

When the first medium is air, then $\sin(c) = 1/n$ where $c$ is the critical angle and $n$ is the refractive index of $n_2/n_1$ (where $n_2$ is second medium and $n_1$ is in air). So, $1/(n_2/n_1)$ ...
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2answers
126 views

Snell's law and Fermat's principle

I have read this sentence on a book about the Snell's law of refraction, referring on a ray that passes from air ($n_1=1$) to glass ($n_2=1.55$): "Snell's equation can be derived from Fermat's ...
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1answer
65 views

Bending a Laser Beam [closed]

We can bend a Laser beam by varying the refraction coefficient of the air. We can bend a Laser beam by dispersing into the air small particles that have the same effect on the Laser Beam and small ...
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2answers
206 views

Is there a formula to calculate the deviated angle of a ray passing through a prism?

I'm assuming the angle of incidence to be the number of degrees from a perpendicular line on the side of a prism the ray starts passing through... I'm trying to figure out the angle the ray would be ...
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1answer
122 views

Why the image is being formed at the surface?

Last week I encountered a very cool optical phenomenon. A photo was sandwiched between the two glass plate to make the paperweight. The cool part is the picture seems to have been pasted on the top ...
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2answers
9k views

Would you see a rainbow from refraction when the sun is in front of you?

I know how rainbows are formed, and why. Usually it is said that the Sun must be behind the observer, in order for its light to be totally reflected inside the droplet and then reach the observer. ...
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1answer
54 views

Curved Light stream?

I was wondering, a while ago, i asked if there is a way to bend light someway, which I got the answer is index of refraction. Which is when light passes through a material it refracts to a certain ...
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2answers
1k views

Refractive index variation with wavelength of light

In my book it is written that $$\text{refractive index} = c/v =\sqrt{\text{permeability} \times \text{permittivity}}$$ The dielectric constant medium is dependent on the frequency of the field....
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2answers
92 views

Why does violet light bend the most? [duplicate]

When white light passes through a prism, refraction occurs and it splits into its seven constituent colours. If the spectrum is obtained on a screen violet light appears much more bent than red light. ...
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1answer
62 views

Correlation between the refractive index and the density

The $v$ propagation speed of light in a transparent medium is related to the $c$ speed of light in vacuum through the relationship, $$\boxed{n=c/v}$$ The constant $n$ is a pure number called ...
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2answers
85 views

Do gravitational waves disperse/refract (like EM waves in a prism)?

I have read this question: What is the relationship between a gravitational wave and a graviton? where kingledion says: Gravitational waves were theorized a century ago and recently ...
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2answers
39 views

Angles of Refraction,Internal reflection and incidence

First ill ask my question in brief and then ill elaborate it below... Theoretically is it that internal reflection occurs within a solid sphere(which is considered to be the denser medium) if and ...
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1answer
237 views

Feynman Lecture 33: Are Fresnel coefficients real?

In the Section 33-6 Feynman says: It is possible to go on with arguments of this nature and deduce that $b$ is real. To prove this, one must consider a case where light is coming from both ...
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2answers
1k views

Refraction: Swimming goggles, short-sightedness, and underwater vision

I have thought of this question due to personal experience. I am short-sighted, and over the last three years my short-sightedness has worsened. Taking a lifeguard certificate again now that I did ...
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1answer
228 views

How does the white color inside/below a rainbow arise?

Inside the rainbow all the colors of the rainbow are joint together to form white light. But how are all these different color cones formed? We see only the outside bands of the rainbow colors but ...
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1answer
316 views

Determining the refractive index of a glass slab using a travelling microscope

In this practical video of finding the refractive index, the reading is being taken by placing the travelling microscope perpendicular to the slab. But I've learned in another video(Frame Shot) if you ...
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1answer
34 views

Calculated focus of an asymmetric bi-convex lens

So I've been working on modeling an optical system using ray tracing. I've finally gotten to the point where I am testing things however I've come across something I'm not entirely sure of. I'm ...
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0answers
31 views

The Refractive Index of Water after Several Heating and Cooling Cycles

If the refractive index of water under a certain temperature, say 20 degreeC, is 1.33334. Will it return to exact the same value after one or several heating and cooling cycles? Or will it shift a ...
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4answers
2k views

Reverse of diffraction

Can we arrange a practical in such a way that the dark and bright bands in diffraction grating be allowed to pass through the same slit to get the original light (i.e the incident light before ...
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1answer
240 views

Difference between thin film interference and Bragg diffraction of electron

Thin film interference is given by: $2dsin\theta=n\frac{\lambda}{n_i}$, where $d$ is the thickness of film, $\theta$ is the angle between incident light and tangent to the surface, $n$ is an integer, $...
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0answers
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Why frequency does not change when light passes through the denser medium? [duplicate]

as far as I noticed always people in physics have a predefined assumption that frequency is constant. whereas we know that the c is the outcom of product of wavelength and frequency. we have different ...
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1answer
215 views

What is Snell's window?

Why is it that an underwater observer can see only a circular "window" and also can't see anything above the separating surface? Does the "window" depend on the depth?
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1answer
44 views

Why does the Complex Index of Refraction take part in the Reflection?

I'm aware that in Optics, the complex index-of-refraction $\eta = n+ik$ is used, which famously leads to the reflection property at an incident angle, i.e. Fresnel's law: $$R=\frac{(n-1)^2+k^2}{(n+1)^...
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2answers
125 views

Does light travel faster in between Casimir plates?

Speed of light is in general $c/n$ where $n$ is a refractive index. But for example introducing two parallel plates with very small spatial separation will perturb the energy density of vacuum ...
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2answers
62 views

Help understanding the speed of light in media with refractive index < 1

I have read the standard explanations on this, but I still have trouble with convincing myself that information is not propagating at faster than the speed c in media of refractive index less then ...
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3answers
2k views

Reflection coefficient as a function of frequency

I am trying to relate the equation for reflection coefficient in oblique mediums to the frequency but can't figure out how the frequency affects the reflection of light. $n_1$= intrinsic impedance of ...
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0answers
45 views

Question about transmission of paraboloidal light waves in bi-convex lens

The question is as follows: Show that a paraboloidal wave centered at $z_1$ is converted by a lens of focal length $f$ into a paraboloidal wave centered about $z_2$, where $\frac1{z1} + \frac1{z2} ...
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2answers
173 views

Reflectivity with Complex Refractive Index

I would like to ask a followup question on a previous post found here. Starting from the general expression for reflectivity: $$R = \left\lvert\frac{n_1-n_2}{n_1+n_2}\right\rvert^2$$ and ...
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1answer
90 views

Do photons “bounce off” of electrons?

I’ve been reading a book, and in one part the author explains how electrons only absorb the wavelengths of light that can take them to an excited state, i.e. that can take the electrons to a higher ...
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1answer
65 views

How do I use a sunstone? How does it work?

I have acquired two pieces of Icelandic Spar (optical calcite) with surface and internal fractures that should be serviceable as sunstones. I have observed the double refraction and cancelling double ...
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2answers
68 views

How do we determine refractive index of a photonic crystal?

Normally, refractive index of a medium is defined as $$n=\frac c{v_\text{p}},$$ where $c$ is the speed of light in vacuum, and $v_\text{p}$ is the phase speed of light in the medium. Phase speed is ...
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3answers
4k views

Why doesn’t a normal window produce an apparent rainbow?

When light refracts in a prism it creates a rainbow. My question is, why don’t all windows or transparent objects create this dispersion, i.e. why is the refractive index dependent on frequency in a ...
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1answer
52 views

Why does the intensity of the scattered light vary when a monochromatic laser is shined into a transparent object?

When a laser is shined into a glass ball such as this video (link) or a bottle of water (link) the light is refracted through the whole transparent body. However, the intensity of the light scattered ...
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2answers
89 views

Is speed of light continuous when entering a medium?

I know that light has the speed $c$ in vacuum and speed $c/n$ in a medium with refractive index $n$. I wonder how this exactly happens - is there some kind of smooth transition? If so, on which scale?...
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1answer
191 views

(7) Will a nearsighted person who wears corrective lenses in her glasses be able to see clearly underwater when wearing those glasses? [closed]

Will a nearsighted person who wears corrective lenses in her glasses be able to see clearly underwater when wearing those glasses?
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2answers
6k views

Why don't light beams refract when they hit a curved surface [closed]

I saw a diagram that showed a light beam hitting a curved glass block (half circle) and nothing happened until it hit the flat surface, in which it refracted. Why doesn't it also refract when it hit ...
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0answers
21 views

Polishing Spherical Refracting surface vs Lens

My text book states that When we polish a spherical refracting surface (sphere) it doesn't behave as spherical surface and mirror .It still behaves as spherical surface. The polished side is just ...
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1answer
52 views

Physical Analogs of General relativity and optics

My Prof told me today there is a 1-1 correspondence between particles in a curved space time, and optics problems in various indices of refraction, extending even as far as black holes. Does anyone ...
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2answers
116 views

Why does a prism refract light into a rainbow? [duplicate]

Why does a prism refract light such that the different frequencies of light “spread out”? The same goes for rainbows, why do the raindrops “spread out” the different frequencies of light?