# Questions tagged [refraction]

Change in the direction of propagation of a wave when its transmitting medium changes. The tag does also apply to index of refraction.

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### Can X-rays travel quicker than visible light in a medium?

I have seen while reading a few books that the refractive index depends on lambda as follows by the Cauchy equation. $${\displaystyle \eta(\lambda )=A+{\frac {B}{\lambda ^{2}}}}$$ From this, the book ...
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### What exactly is "dense" in Optical Density?

My book states that: When passing from one medium to another, if light slows down, the second medium is said to be optically denser than the first medium, and if light speeds up, then the second ...
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### RAY OPTICS ( LENS AND SPLITTING OF LIGHT ) [closed]

I came across a question in my book where I was asked if white light splits when it passes through biconvex lens. Could someone help me with this. I am a bit confused. I feel it won't split.
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### Image Formation at a Spherical Refracting Surface

I was thinking about refraction at spherical refracting surfaces and what the required conditions be for the formation of a real or virtual image? I thought I could use this formula: \begin{equation*} ...
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### Can we apply lens makers formula when medium on either side of the lens is different?

Lens maker's formula, which is $\frac{1}{f} = ({n_{liquid}{-1}}) [(\frac{1}{R}) - (\frac{-1}{R})]$. Can one apply lens makers formula when medium is different on both sides? If NO, why? Should we use ...
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### Can we apply lens makers formula when medium on both side of lens is different? [closed]

Lens maker's formula here, which is $\frac{1}{f} = ({n_{liquid}{-1}}) [(\frac{1}{R}) - (\frac{-1}{R})]$ How can one apply lens makers formula when medium is different on both sides?
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### How does a rainbow show all of its colours?

My question is tied closely to this one, asked a while back on the website. As far as my understanding goes, a rainbow is formed by sunlight undergoing two refractions and a reflection inside ...
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### Finding Shift due to Refraction in Multiple Slabs when the object and viewer are in different medium [duplicate]

So, suppose we have three rectangular slabs each of varying refractive indices(R.I.) and thickness. We have a real point object to the left of the first slab and we have an observer to the right of ...
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### Effective Radius of Earth [closed]

Hi I am looking for an equation for the effective radius of the Earth. I have a refractive index given by $n^2(r) = 1+\frac{\alpha^2}{\beta^2}$. How would I work out an equation for the effective ...
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### Can we tell on which side of a lens an image appears?

Suppose I look through a single, thin, converging lens at an object on the opposite side. Depending on where the object is placed, the lens will either produce a real image on the side of the lens ...
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### Does the speed of an object underwater change when viewed above?

Let's say a submarine is coming to surface with a velocity $v$ normal to the surface of water and let's say you are the admiral of the navy viewing the submarine from the top. The submarine is exactly ...
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### Sign Convention in Ray Optics

While solving questions on Refraction due to 2 spherical surfaces the sign of the image formed after the first refraction (here at '$A$') depends whether the image formed is towards left or right side ...
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### Geometric optics explanation of lateral (transverse) chromatic aberration

The majority of pictures explaining lateral(transverse) chromatic aberration look like this Here the focal point for red light is shifted closer to the optical axis and the focal point for blue light ...
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### How does the combination of lens create a sharper image?

There's a line in a book which states that the combination of lens helps create a sharper image, but I don't understand how. Does more magnification mean sharper image?
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### What happens to the time period when refraction occurs? [duplicate]

I was studying light and had a doubt that when refraction occurs (rarer to denser just assuming) then frequency remains same but lambda (wavelength) and velocity decrease. But I cant quite figure out ...
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### Would an accelerated-time space region deflect projectiles?

Suppose a spherical region in space in which time goes faster. Would projectiles shot at it be deflected away, as light is deflected by a material with a lower refractive index? Edit: This would also ...
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1 vote
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### What is the theoretical range of temperature the air must be in order to reflect/refract light (for a volumetric display)?

Well, the only question I found in this website about volumetric displays on air was this one, but it specifically suggests making air denser in order to make it work, but my question is specifically ...
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1 vote
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### Wavefront of a cylindrical beam of light

The given question states that a cylindrical beam of light with refractive index of the beam varying as u=A+B/r^2 where r is the distance form the axis of the beam. Now the questions asks us the shape ...
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### Image formation from refraction through a water surface (plane diopter)

Let's suppose that an object sits in water. The light rays comings from that object will get refracted at the water surface at different angles and the refracted rays are not concurrent (do not meet ...
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### Relation between time taken by light to pass through a glass slab and the refractive index

I came across the following question as an example in my book: A glass slab has its left half of refractive index $\mu_1$ and right half of refractive index $3\mu_1$. What is the effective refractive ...
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### On a minima problem in optics

I have trodding through a calculus textbook, more specifically — through a chapter on the methods of obtaining the extrema of functions using derivatives, including certain problems in optics (Fermat’...
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### Why is the refractive index of blue light larger than red light in water while the refractive index of radiowaves is larger than both?

So I thought the reason why radio waves have a relatively high refractive index in water is because they have a low frequency which increases the permittivity, but blue light that has a higher ...
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### Rainbow reflections from salt crystals

Especially on a sunny day in the winter or spring, I often notice faint rainbows when I look down at the edge of the road by the curb. I am not sure what causes these rainbows, but I believe that ...
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### What are the difference between step-index and graded index fiber?

I was starting to study optical fibers and I came to the chapter: Classifications of optical fibers. Here I read about singlemode and multimode fibers, regarding the latter he explained the difference ...
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### Is this floating ship really a mirage? [duplicate]

The media is full of stories of rare pictures of flying ships. They go on to describe them as mirages. These images are described as rare. The picture I have uploaded was taken on Good Friday 2022 ...
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### Why aren't negative diopter glasses invisible?

If the diopters of a set of glasses determine the thickness, and higher diopters determine a thicker glass, why aren't negative diopter glass lens invisible?
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### What is the smallest value of the incident angle in Bragg's law?

The title of my question basically is what I want to know. In Bragg's law, $nλ = 2 d \sin{\theta}$, if we want to find, let's say, $d$, and know only $\lambda$ and $n$, but not $\theta$, what could be ...
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1 vote
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### Where can I find tables of the refractive index (real and complex part) or dielectric function as a function of frequency for different materials?

I need this information to do simulations for my master's thesis but I don't know if there is a bibliography or a repository on the internet with this information. They are simple materials, water, ...
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### Mechanism of speed change in refraction [duplicate]

Light changes speed when traveling from one medium to another. What i want to know is how exactly does the speed of light change. A solid like glass, is again just made up of atoms made of electrons ...
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### Prism deviation angle for small angles

Consider the following scheme for monochromatic light refracting through a prism, with the deviation angle $\delta$:                                               Let $\theta_1\ \wedge\ \alpha\ll1$ . ...
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### Translucent materials, like frosted glass, do have a refractive index?

I'm an architectural lighting designer in Mexico and I know the basics of absorption, transmission, reflection and refraction of materials. But I can't find anything about translucent materials like ...
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### What would you see at the focal point of a perfect magnifying glass?

What image would appear on a perfect magnifying glass in perfect vacuum with an object at exactly the distance of the focal point?
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### Understanding some implications of Fermat principle

I am modelling the propagation of light rays from one point to another, with some object in between, in this case a disk to simplify matters, and I compared the travel times of a refracted ray and a ...
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### Confusion over the critical angle

At school, I was taught to use $\mathrm{sin}\ c = 1/n$ to calculate the critical angle, given it is from a medium to air. I tried deriving a general formula for critical angles for every pair of ...
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### Why does the wavefront remain a line when light enters another medium?

I've been trying to understand refraction, and even though I thought my background in mathematics would ensure my success, I've been mistaken. Indeed, I've been reading the Wikipedia article, and it ...
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### What can be the possible causes for variation in stress-induced birefringence in an isotropic material?

Birefringence is the phenomenon of a material having a refractive index that depends on the polarization and propagation direction of light. When an unpolarized light passes through such a material, ...
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### What is the acceleration of light (photon) in vacuum? [duplicate]

We all know that the speed of light is 299792458m/s, but what is the acceleration of photons? That is to say, does the photon have a speed transition from zero to the speed of light?
1 vote
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### Is it possible to see behind the horizon because of light refraction?

I was debating a flat earther who claims that he was able to see what he shouldn't see if earth was spherical He stood on a hill with height of 201 m and used his camera to see all of Dubai which was ...
3k views

### Where does the "water" come from in a mirage?

First, I would like to clarify that I know why a mirage is formed, what I want to know is why is it that when a mirage is formed it appears that a pool of water is present. Like for a palm tree in a ...
1 vote
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### Reflection at asymmetrically shaped refractive-index profile

Hi. I have a question on reciprocity in optical reflection. We have a refractive index profile (as a function of x) that continuously varies (Figure). At x=-inf and +inf, n = n1. Around x=0, the ...
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### Dispersion of light at the boundry of vaccum and air

We know , refractive index of medium is dependent of wavelength . So why doesn't the light get dispersed at the boundry of vaccum and air(as in case of prism), , when it travel from sun to earth .
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### Refraction of mechanical waves

Everyone knows about the refraction of light. But what about refraction of mechanical waves? With a quick research I was able to find that sound waves and water waves do undergo refraction. But I am ...
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### Why is the critical angle the largest angle of incidence for which refraction can still occur?

When I look up "critical angle", it's defined like the following: The critical angle is the angle of incidence where the angle of refraction is 90° source If I look up what refraction ...
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### Factors affecting Refractive index

I have a doubt that with increase in temperature the refractive index is decreasing but refractive index of ice is lower than water????
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### What is refractive index of a hollow glass container with a liquid inside?

Suppose that a thin hollow glass slab with a refractive index of $1.5$ contains a liquid inside, which has a refractive index of $\mu$, and $\mu \neq 1.5$. If I now send a laser light at the medium ...
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### Why we see only one rainbow at some far away and not like many separated by some distance but making that same angle of 42°? [duplicate]

We know that angle needed to see a rainbow assuming sun is at horizon is 42° but then why will that rainbow formation be unique and why not at that angle many rainbows be form in that angle why just a ...
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### Why does the wave velocity of EM signals in a wire depend on the insulator's permittivity?

I'm in an electromagnetism class and struggling with a concept. The textbook derived several equations which state that the wave velocity of an electrical signal in a transmission line depends on the ...
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### What is the angle of a ray passing through a thin lens?

Let's say I have a thin lens model of an optical system. When I have a ray that is parallel to the optical axis, the situation is quite standard - the ray refracts and passes the focal point f (see my ...
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