Tagged Questions
2
votes
2answers
28 views
Penetration of light in the atmosphere
While I was considering an answer to this question, I wondered how much light that enters the atmosphere reaches the ground without colliding with air molecules—if any. I've taken a good bit of ...
1
vote
1answer
42 views
Apparent and real depth object in water [closed]
Did I get my formula right? Seems like the correct answer is $d_o = 1.33 \times d_i$ but I thought the formula I should use is $d_i = - \frac{n_2}{n_1} d_o$
3
votes
2answers
121 views
Physical explanation for why total internal reflection occurs
I have been trying to understand total internal reflection (and have read several posts on this site already). Mathematically, I feel that I understand how the evanescent wave decays exponentially as ...
2
votes
1answer
36 views
How much refraction occurs as a fraction of all reflection and refraction?
When light reaches a boundary between materials below the critical angle, some of it refracts and some of it reflects. For example, glass acts as a partial mirror with a dark background.
Assuming ...
1
vote
2answers
162 views
Why does light not refract when incidented perpendicularly?
I had read that light does slow down in glass because photons interact with atoms in glass. They are absorbed and re-emitted and during this phenomenon it's speed decreases. See also this and this ...
1
vote
0answers
11 views
Speed of Light in a Medium [duplicate]
For light travelling in a medium with refractive index greater than one:
The "average" speed of light is slower than the speed of light in a vacuum. As far as I know, the instantaneous speed of light ...
4
votes
2answers
179 views
Goldfish perspective
What does the world look like from the Goldfish point of view, from inside a spherical aquarium?
If our eyes were inside, would we be able to see the straight lines, focus on different objects and ...
5
votes
3answers
313 views
How do “holographic plates” work?
I asked a question about laser stage lighting over at Audio Video Production, and received an excellent answer that explained that laser clusters are generated from a single beam via something called ...
3
votes
2answers
148 views
Effect of gas or liquid within a compound lens system
Hi my question is if a compound lens system if filled with gas or a liquid how does it affect the system when compared to the lens system being separated by air alone. Does this affect the focal power ...
5
votes
2answers
231 views
Photon energy - momentum in matter
$E = h\nu$ and $P = h\nu/c$ in vacuum.
If a photon enters water, it's frequency $\nu$ doesn't change.
What are its energy and momentum : $h\nu$ ? and $h\nu/c$ ?
Since part of it's energy and momentum ...
2
votes
3answers
157 views
Difference in velocity of light in change in medium
It is often seen that according to physics the light changes it's velocity according to the medium through which it is traveling. So can it be explained that why so happen?
-1
votes
1answer
77 views
Determine when a light is going into the object [closed]
Please look at this image: (http://mypages.iit.edu/~smart/acadyear/refract.gif)
How can I determine when light is going into the object?
Actually, if there is, what is the simplest way to ...
0
votes
1answer
110 views
Width of Gaussian Beam and Refractive Index
I know that in free space, the width of a Gaussian beam can be written as $W=W_0\sqrt{1+(\frac{z}{z_0})^{2}}$. However, I was wondering if it was possible to express this width as a function of ...
7
votes
3answers
288 views
Why do rainbows have distinct colors?
When I searched on the Internet for the reason of formation of rainbows, I got many explanations like this one & this. All the explanations consider only one spherical water droplet (like this ...
2
votes
0answers
82 views
How can I estimate the elasto-optic coefficients ($p_{11}$ and $p_{12}$) of a material?
I am attempting to estimate the elasto-optic coefficients ($p_{11}$ and $p_{12}$) of $\mathrm{TiO}_2$ and $\mathrm{ZrO}_2$, where $p_{11}$ and $p_{12}$ refer to the elements of a strain-optic tensor ...
2
votes
1answer
331 views
What are the properties of the partially polarized light on refraction?
When a ray of ordinary light is passed on the surface of the water the reflected light will be completely polarized( vibrations in one plane).
My question is what will be plane of vibration in the ...
2
votes
1answer
59 views
In electro-optic material, what is happening to the structure of the material for the index of refraction to change?
I apologize if electro-optic material is not the correct word.
As I understand it, when an electric field is applied to an electro-optic material, the index of refraction changes in proportion to the ...
-6
votes
1answer
195 views
Speed of light is not fixed?
In my research, I found that the speed of light is not fixed. IS it true?
Namely, We know that light refracts when the medium it travels through changes. Actually, light travels in the same medium ...
4
votes
4answers
1k views
How to bend light?
As we all know that light travels in rectilinear motion. But can we bend light in parabolic path? If not practically then is it possible in paper? Has anyone succeeded in doing that practically ?
3
votes
1answer
171 views
Fermat principle: which index of refraction?
I am somewhat puzzled by a common formulation of the Fermat principle (light travel time), because it contains index of refraction related to phase velocity while light travel time through a slab of ...
2
votes
4answers
137 views
Light refraction and causality
One way how to look at refraction by a dielectric medium like water or glass is that (phase) velocity of light decreases because it is the wavelength rather than the frequency of the light which ...
3
votes
5answers
2k views
Is it possible to witness a circular rainbow?
What conditions would make it possible to see a naturally occurring fully 360° circular rainbow? Would it even be possible?
5
votes
3answers
1k views
Can anyone explain to me why light is not dispersed into a spectrum through a parallel glass slide, but only through a prism?
The question pretty much sums up what I need to know. Why is it that light only gets dispersed into a spectrum when travelling through two non-parallel sides(like a prism) and not through something ...
-2
votes
2answers
241 views
About change in velocity of a light wave as it enters a different medium [closed]
$\dfrac {sin\theta1}{sin\theta2}=\dfrac {v1}{v2}=\dfrac {n2}{n1}$
I understand this equation, but what is the velocity of a light wave going through air and what is the velocity/change in velocity as ...
1
vote
3answers
378 views
Why does change in speed of a wave make it refract?
When a light wave enters a medium with a higher refractive index (e.g. from air to standard glass) and its speed decreases, why does that make it refract/bend?
I understand that wavelength decreases ...
2
votes
3answers
2k views
Clarification needed in the concept of apparent depth & real depth
I understood the concept of apparent depth from here:
But one thing I didn't understand is, will there be difference in the real depth and apparent depth when we are looking not at an angle as ...
5
votes
1answer
491 views
Why do mirages only appear on hot days?
A previous question asked why the road sometimes appears wet on hot days.
The reason is that when there's a temperature gradient in the air, it causes a gradient in the index of refraction, causing ...
0
votes
2answers
226 views
Air vs Glass refraction coefficient
I have a rather strange question, let's say I can play with the temperature and atmospheric pressure conditions in a sealed room. What will I need to do to make the air's refraction coefficient ...
6
votes
6answers
2k views
Why does light change direction when it travels through glass?
This was explained to me many years ago, by a physics teacher, with the following analogy:
"If someone on the beach wants to reach someone else that is in the water, they will try to travel as much ...
2
votes
0answers
118 views
Modeling a spray painted polyurethane surface reflection
I'm modeling light interaction/reflection from a fiberglass surface with polyurethane epoxy (that is very reflective) that has been spray painted with a matte black paint. I'm looking for some input ...
1
vote
1answer
218 views
Does coverslip thickness matter for high NA oil immersion objectives?
This question is related to Impact of covering glass on lens performance.
I use a 63x TIRF objective with a numerical aperture of 1.46 and oil immersion.
The immersion oil has an index of ...
1
vote
0answers
185 views
What defines the thickness of a Nomarski prism?
Lets say I want to design a Nomarski prism that would split the ordinary and extraordinary beam by an angle of 0.32 mrad. I used a raytracer to find the internal angle between the quartz wedges.
...
10
votes
3answers
883 views
What really cause light/photons to appear slower in media?
I know that if we solve the maxwell equation, we will end up with the phase velocity of light is related to the permeablity and the permitivity of the material. But this is not what I'm interested in, ...
4
votes
2answers
982 views
intensifying a light source
When trying to intensify a beam of light by refracting it through a lens, (as in a lighthouse fresnel system or similar railroad style switch lamp from years past), is the beam intensity increased by ...
1
vote
1answer
490 views
Refractive index of organic solvents in near-infrared
I wonder if the refractive index of acetone, ethanol, methanol, heptane was measured in the range above 830 nm. The site refractiveindex.info provides it only for visible, and I couldn't find any ...
2
votes
3answers
677 views
Reconciling refraction with particle theory and wave theory
I have searched the web for good answers to why refraction occurs when light moves from one medium to another with different density. I have limited background in physics and want to know if there is ...
5
votes
5answers
3k views
Eyes open under water
Yesterday I looked underwater with my eyes open (and no goggles) and I realized I can't see anything clearly. Everything looks very, very blurry. My guess is that the eye needs direct contact with air ...
4
votes
3answers
2k views
How can I determine transmission/reflection coefficients for light?
When light rays reflect off a boundary between two materials with different indices of refraction, a lot of the sources I've seen (recently) don't discuss the relation between the amplitude (or ...
