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16
votes
1answer
2k views

Why is not everything transparent? [duplicate]

There is a related question on this site here: Why glass is transparent? Which explains that glass is transparent because the atoms in glass have very large energy differences between energy levels ...
9
votes
4answers
623 views

Why do the edges of glass blocks create a shadow?

I have always observed that the shadow of glass blocks becomes darker as the glass is moved away from the surface where the shadow falls. And I know this is because refracted light rays from the glass ...
3
votes
2answers
517 views

Why aren't clouds multi-colored?

Clouds are made out of tiny droplets of water. These droplets, to my understanding, act like tiny prisms (which is why there are rainbows after rain). From my line of thinking, if we had a room with ...
1
vote
1answer
34 views

What's wrong with finding the maximum refraction angle? [closed]

I am wrong with this derivation of $1 = \mu^2$ for arbitrary $\mu$ obviously, but I can't find what's wrong. $\delta := \theta_{1} - \theta_{2} $ where $\frac{\sin \theta_{1}}{\sin \theta_{2}} = \mu_{...
0
votes
3answers
745 views

If light slows down while passing through a material, does it speed back up while in a vacuum?

Light slows down while passing through, say, water. After passing through the water, does the light speed back up to the "speed of light"? If so, how and why?
1
vote
2answers
385 views

How come lenses alter the path of photons?

From what I know, photons are theorized particles and believed to be massless (just energy) and travel at the speed of light. How come a lens, which is an object made of atoms, can bend a light path? ...
1
vote
0answers
546 views

How to solve this problem : A glass sphere of radius 1 m and refractive index 1.5 is silvered…? [closed]

Problem: A glass sphere of radius 1 m and refractive index 1.5 is silvered at its back. A point object is kept at a distance of 1 m from the front face, as shown in the figure. Find the position of ...
5
votes
3answers
5k views

Why should angle of incidence be equal to angle of emergence for minimum deviation in a triangular prism?

When I was solving questions on Ray optics I encountered a question wherein I had to prove that when a ray of light undergoes minimum deviation through a triangular prism then both the angles of ...
0
votes
1answer
95 views

Kerr Effect; Electro-refraction

First post here. is is possible to observe the Kerr effect in transparent materials, at low voltages (such as 3.8V)? If so, can you refract light enough to distort an image, in a way similar to that ...
2
votes
2answers
489 views

Polarized light in single mode fiber

In single mode fiber the light propagates in two orthogonal planes. Input will be linearly polarized light, which state of polarization will be on output and why? And if there will be some different ...
4
votes
1answer
4k views

How do opaque materials have an index of refraction?

The index of refraction defines how much light is bent as it passes through an object, right? So how can opaque objects, which don't transmit light, have a value for the index of refraction? (e.g., ...
1
vote
1answer
275 views

Will the ray of light follow the laws of reflection at the interface of two media?

Suppose at the boundary of two optical media,of different refractive indices a mirror is kept perpendicular to surface of the boundary.If a ray of light travels through one of the media and then ...
3
votes
2answers
231 views

Is it possible to create an optical medium where sound can travel faster than light?

The speed of light decreases with increase in the density of the optical medium whereas the speed of sound increases with increase in the density of the medium. So is there any possibility to ...
9
votes
1answer
640 views

If refraction slows down light, isn't it possible to hold light still?

I have a quick question about the refraction of light, and I'm sorry if it seems a bit simplistic or even stupid, but I'm still learning. We know that when light passes through a denser medium, it ...
2
votes
2answers
115 views

How the speed of light is constant in the universe if it decreases in water and glass and some other objects? [duplicate]

My teacher told me that speed of light is constant in the universe. But in optics it is clearly shown that speed of light slows down in some objects. Please help.
2
votes
0answers
116 views

How does refraction work? [closed]

https://www.youtube.com/watch?v=YW8KuMtVpug&feature=iv&src_vid=CiHN0ZWE5bk&annotation_id=annotation_187211 Start the above video at 8:15. How does the phase velocity affect the apparent ...
0
votes
0answers
85 views

Index of refraction for travelling EM wave problem

Let $n_1$ be the index of refraction of the first medium and $n_2$ be the index of the second medium. When $n_2>n_1$, then for an incident angle of $90^{\circ}$ we get a refracted light at a ...
7
votes
2answers
1k views

How can a slowed light ray bend?

If light is traveling through air, it slows down and ends up bending. But how? If I'm running straight, and I get slowed down, shouldn't I still be running straight?
0
votes
0answers
22 views

Can measuring the refraction index in an object measure the strength of the quantum gravity between atoms of the object? [duplicate]

Is measuring the refraction index of an object a way of measuring the strength of the gravitational force between the atoms of the object (measuring quantum gravity)? From reading Snell's law of ...
0
votes
1answer
59 views

How long will the light exist inside the sphere?

Ok, so let's say we have a very thick, but hollow, metal sphere. The inside of the sphere has a radius of 100 meters. The sphere also has a door that can be opened and closed and when closed makes an ...
0
votes
0answers
52 views

What is A2L refractive index polynomial?

I'm working with a photonic modelling software and in the manual I saw that I can specify refractive index of modelled material with following polynomial: $$n(\lambda)=c_0+c_1/(\lambda-\lambda_0)+c_2/...
0
votes
1answer
2k views

Angle of minimum deviation

A prism of angle $60^\circ$ deviates a ray of light through $40^\circ$ for two angles of incidence which differ by $11^\circ$. What is the refractive index of the glass of the prism? If we are given ...
0
votes
1answer
99 views

Differences in speed of light calculations in glass

I wanted to determine the speed of light in glass by using both of the following formulas : $$v = \frac{1}{\sqrt{\mu \epsilon}} \simeq \frac{1}{\sqrt{\mu_0 \epsilon_r \epsilon_0}} \;\;\; \text{and} \;...
1
vote
1answer
700 views

A material with very high refractive index

Suppose we have a material which has a very, very high refractive index, say 30-50. The critical angle for this material would be very small (1.5-2 degrees). Will the said object be even visible at ...
2
votes
2answers
555 views

How light splits up into different colours when passed through prism using QED?

I want to know how light gets splits up into different colours when it is passed through prism? How light interacts with atoms and electrons of the prism? Can someone explain this to me using Quantum ...
2
votes
2answers
39k views

Why is the index of refraction different for different wavelengths? [duplicate]

The index of refraction can be written as $$n=\frac{\lambda_v}{\lambda_m}$$ where $\lambda_v$ is the wavelength in a vacuum and $\lambda_m$ is the wavelength in the medium. I’ve been told that since ...
0
votes
1answer
68 views

Can we measure the height of clouds using the sunset?

I was watching the sun set in San Francisco. As the Earth turns away from the Sun the tallest buildings remain lit longest. Light bending in the atmosphere allows this to last a bit longer. So, what ...
3
votes
1answer
1k views

Why do we use the index of refraction for yellow light?

When we do problems with optics and refraction, we’re usually given a set of indices of refraction to work with; for example, the index of refraction in air is about 1.00, the index of refraction in ...
0
votes
2answers
199 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 ...
-1
votes
1answer
185 views

Why we don't observe spherical rainbow?

We have seen or heard of rainBOW and circular rainbow but not any other shape probably due to the shape of water droplets. My question is why can't we see a spherical rainbow?
42
votes
4answers
10k views

Do rainbows have ultraviolet bands and infrared bands?

We have seen that rainbows looks so colorful as we are only able to see only the visible light. But Do they also have ultraviolet bands and infra-red bands, that we are unable to see? I know someone ...
2
votes
1answer
70 views

Odd order of colour fringes around cloud

The other day I took this photograph of a thundercloud that moved between myself and the sun. Around the edge of the cloud there were some coloured fringes that I first took to be a variant on a ...
1
vote
1answer
99 views

Do the mediums decrease or increase the speed of light? (source to target) [duplicate]

If sun is the source of light then is it possible that the speed of light might increase depending on the mediums its going through or its not possible.
14
votes
3answers
7k views

Is true black possible?

Black is the absence of light because it absorbs light, but when we create black paint or black objects, light is always reflected, either in all directions in matte or smoothly in shiny black objects,...
0
votes
2answers
465 views

Could time dilation bend the path of a photon? Does time dilation have a refractive index?

The main question I am getting at is, does time dilation have a refractive index? What I mean is, if I were to shoot a laser past a black hole, would the laser's path "bend" strictly from time ...
1
vote
1answer
882 views

Determining the path of a light ray

Let's consider a ray in the plane $xy$. Let the refractive index be defined in any point of the plane with the function $n(x,y)$. In time $t=0$ the ray is located in coordinates $(x_0, y_0)$ and its ...
0
votes
1answer
217 views

Difference between speed of light and of bullet after passing through a barrier [duplicate]

I just read that, when a ray of light traveling in vacuum at $c$ strikes a glass slab, its speed decreases and then when it re-emerges it gets back to its original speed i.e $c$. If I draw a ...
9
votes
4answers
46k views

Why does red light travel faster than blue light?

I know that light of all frequencies travel at the same speed in vacuum. But I wonder why their speed differ in any other medium, why does red light travel faster if it has less energy than blue ...
5
votes
1answer
2k views

What causes these rainbow effects using a polarizing filter on an airplane?

I know that light reflected from a surface at 45° is polarized and that for a similar reason skylight arriving from a direction orthogonal to the sun is polarized too. Photographers make use of this ...
3
votes
1answer
2k views

Refraction of light marching band analogy

When trying to understand the refraction of light when it hits a slower medium, lots of people seem to be enlightened by the 'marching band' or 'marching soldiers' analogy, which 'explains' that when ...
2
votes
2answers
77 views

Velocity of light

Velocity of light decreases as it enters a more optically denser medium. So how far can the velocity of light be reduced? Which object has the highest refractive index?
0
votes
0answers
15 views

Is the link between shadows a refraction of the light? [duplicate]

When two objects in the sunlight approach, if you look at their shadows, they form a link when they are really close, is that an example of refraction? If so, is it the same as the refraction we see ...
1
vote
3answers
2k views

Frequency dependence of the speed of light in air

According to this link, the speed of light of different colors in a medium should be different. But if the refractive index of light in air is 1 then this means that the speed of light in air and ...
1
vote
0answers
71 views

Making sense of sinogram of perspex block in air

I'm confused trying to visualize what happened exactly during this experiment: Setup with a laser and a photo diode on the opposite side. A perspex block (2x2cm) in between. Take 200 measurements ...
0
votes
0answers
371 views

Reflection and refraction of light [duplicate]

When a light ray strikes an interface a part of it gets reflected, a part of it gets absorbed while another part gets refracted. Why does light reflect? Why does it refract?
6
votes
1answer
3k views

Why does light not slow down?

Clearly light bounces off of things, going really really fast. I'm curious to understand how light interacts with matter in order to bounce without: Applying force to the object Losing speed So my ...
5
votes
5answers
628 views

How is it possible for the wavelength of light to change in a medium?

So my physics class has just finished a long unit on optics while at the same time I've been trying to teach myself relativity. I admit my understanding is probably rudimentary, but I figured all the ...
-2
votes
1answer
173 views

Experiments to the question : why wet is dark?

How can we prove the explanations for: why clothes get dark when they are wet, by experiments?
2
votes
3answers
872 views

How to improve the visibility of light without increasing the brightness?

I am not sure whether or not this is the right SE site to post this question on but I'm sure someone will inform me of my mistake soon enough if it is wrong. Basically I am an Electronic Engineer and ...
0
votes
0answers
44 views

What does the refractive index depend on? [duplicate]

I've always thought refractive index is dependent on the density of the material. The more denser, the more refraction. But kerosene whose density is higher than water has refractive index less than ...