1
vote
1answer
29 views

Imaginary number for extinction coefficient in complex refractive index

In complex refractive index on a material, $n=n'+ ik$, the imaginary part $k$ is physical meaning, as it shows absorption in the material but it is an imaginary. How we measure an imaginary values in ...
0
votes
0answers
27 views

Difference between the increase in optical path due to refraction and that due to reflection

If we place two glass plates of refractive index n and each having thickness t,on the way of a light ray the increase in optical path becomes (S2P-S1P)=2(n-1)t due to refraction through them,and the ...
1
vote
0answers
16 views

Non-uniform lens flares [duplicate]

I assume -- and maybe wrong -- that lens flares, in photography, are caused by light getting "trapped" inside the curved lens and bouncing around (due to refraction and non-perfect total internal ...
14
votes
2answers
499 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. ...
0
votes
2answers
65 views

Why does the light travel slower in denser medium? [duplicate]

Wikipedia says that "in general, the refractive index of a glass increases with its density." And the refraction index of water vapor is less than ice, and even less than liquid water. Is there any ...
1
vote
1answer
81 views

Refractive Index formula for denser to rarer medium

I learnt that the formula for refractive index when light travels from rarer to denser medium is (sin i / sin r) where i = angle of incidence r = angle of refraction Is the same formula used for ...
1
vote
1answer
56 views

Deriving and gaining intuition for the equation for the index of refraction $n = \sqrt{\mu_r\epsilon_r}$

I've come across the equation in the title. It relates the index of refraction of a substance to the square root of the product of the relative permittivity and the relative permeability at whatever ...
3
votes
1answer
110 views

How to compensate ray displacement caused by refraction in glass slab

I need a nudge in the right direction, i guess (this is not a homework question). I want to calculate the total length of a ray from an emitter to a target which passes through a slab with known ...
1
vote
1answer
74 views

Apparent depth and the viewing angle [closed]

Does the viewing angle of a person observing a coin placed in a bucket of water affect the apparent depth in any way?
0
votes
1answer
101 views

Why is a rainbow curved in shape?

Why is a rainbow curved in shape? When dispersion of light takes place, light splits into seven colors, but when rainbow is formed it appear to be bent. Why does this happen even though light travels ...
0
votes
1answer
53 views

Pfund's method for refractive index

I wish to obtain the refractive index of a smooth surface using only a laser of given wavelength and a light sensor. I thought of using the Pfund method (attached), but I can't understand how the ...
2
votes
2answers
47 views

The velocity of light changes from one medium to another, but does its energy change?

Does energy of light change when a light travels from a medium to another of different optical density?
2
votes
2answers
80 views

What really makes a rainbow happen?

Yes, a rainbow is formed when a raindrop refracts light, but why then does the whole sky not become a huge rainbow when it rains? Would the light not be dispersed into ordinary 'white' light? What ...
0
votes
3answers
157 views

Refraction through prism

We know that the light gets refracted when it enter a medium low/high refractive index. But why light is not refracted when it comes out from the vertex of a prism.
3
votes
1answer
133 views

Is there a way to increase the speed of light itself?

When light enters materials it slows down due to its refractive index (due to absorbing and re-emission of photons). But, is there a way to increase the speed of light itself? Can there be some ...
1
vote
1answer
104 views

What causes refraction of visible light? [duplicate]

Refraction is the bending of a wave when it enters a medium where its speed is different. The refraction of light when it passes from a fast medium to a slow medium bends the light ray toward the ...
1
vote
1answer
49 views

Polarization in Nicol prism

My book reads "When unpolarized light is incident on nicol prism (made of 2 crystals joined by Canada balsam a type of glue) it divides into 2 rays, both rays are plane polarized and electric field ...
1
vote
1answer
118 views

Finding out the minimum deviation angle [duplicate]

Let a light incident on a prisom at right angle. I want to determine the minimum deviation angle. I know a relation $$ \frac{\cos i_1}{\cos r_1} = \frac{\sin i_1}{\sin r_1}$$ and minimum angle ...
4
votes
3answers
56 views

Why don't fogbows appear on clouds?

As far as I know clouds are lot of small droplets condensed in air. If droplets are large enough we see a rainbow. If they are small we see a fogbow. Although the size of the droplets are big enough ...
1
vote
2answers
51 views

Temperature-induced wavelength shift of optical coatings?

Optical coatings designed for reflection or anti-reflection are made of many thin layers which will expand when heated. What will the effect be on the wavelengths the coating will reflect when the ...
0
votes
1answer
54 views

Dispersion relation of silicon

In the case of dispersion relation of silicon having crystal plane orientation 111; what is the Sellmeier's equation for refractive index $n$ of silicon orientation 111 & what it's extinction ...
2
votes
1answer
174 views

Apparent size of objects under water

A friend of mine has a homework question and we're having some trouble figuring out what physical mechanisms come into play for this. An underwater swimmer sees a spherical air bubble that appears ...
1
vote
2answers
148 views

Refraction of light in medium

Given that the plane $y=0$ separates the vacuum ($y>0$) from the optical medium ($y<0$), I would like to calculate the trajectory of a light ray starting at the point $(x_1,y_1)$ and ending in ...
2
votes
1answer
772 views

Analytic solution for angle of minimum deviation?

Consider a simple prism with a prism angle $A$, angle of incidence $\theta_1$, angle of emergence $\theta_4$ and the first and second angle of refraction as $\theta_2,\theta_3$. the refractive index ...
2
votes
3answers
112 views

Law of refraction from Scalar Diffraction Theory

I am trying to figure out if Snell's Law for refraction can be derived from Scalar Diffraction Theory. The setup is this: light (plane wave, with wave vector $\vec k_i = (k_x, k_y, k_z)$ ) falls on ...
5
votes
1answer
147 views

Why Negative refractive index is negative

$n=\sqrt{\epsilon \mu }$ Negative refractive index happens when permittivity ($\epsilon $) and permeability ($\mu $)of a material is negative. My question is, if permittivity and permeabilitity of a ...
1
vote
2answers
110 views

Good explanation of a real image?

Okay well I've started to study phys chem in school recently and I honestly can't get my head around what a real image actually is I've asked my teacher to demonstrated it but she's quite lazy, and ...
2
votes
1answer
142 views

Faster than light in plasma

Some plasmas have a refraction index of less than 1. In these plasmas the phase velocity of light can be faster than light-speed. But the phase itself won't transfer information, so no paradox occurs ...
1
vote
0answers
114 views

If a beam of light follows the path $y(x)=y_0\sin(x/y_0)$, what is the index of refraction?

An exam question that showed up while I was studying: A plane wave refracts and follows a ray given by the equation $y=y_0\sin(x/y_0)$ where $y_0$ is a constant. Find the refractive index $n(y)$ ...
1
vote
2answers
166 views

Calculate the polarization vector on reflection or refraction from a dielectric interface

I am interested in ray-tracing polarized photons. I have code that works very well for unpolarized light. When a ray hits a dielectric interface the photon is either reflected or refracted by ...
2
votes
1answer
118 views

Why does a mirage disappear as you approach it?

Related: why do mirages only appear on hot day? The title says it all: why does a mirage disappear as you approach it? The related question does not answer this.
2
votes
2answers
129 views

How far can you scatter light using a prism?

If I were to scatter light how far do you think it will disperse and what prism is the most effectively scatters light?
1
vote
1answer
36 views

Full refraction in fibre optics

Well in a problem I had to calculate the maximum amount of "reflections" in a glass fibre optic pipe (index of refraction = 1.3, width of 20 micrometer and length of 1 meter). I am a bit blocked on ...
4
votes
2answers
189 views

Shape of the rainbow

I have watched Walter Lewin's lecture(http://www.youtube.com/watch?v=6QVbE_tU2sA) which was about the rainbows. But there is still a question bothering me. I understood the first part of the ...
2
votes
3answers
251 views

How Does $\epsilon$ Relate to the Dampened Harmonic Motion of Electrons?

I realize that the permittivity $\epsilon$ of a substance is easily calculated based on diffraction angles, but I am not satisfied with merely measuring it experimentally. I wish to understand its ...
2
votes
1answer
192 views

Reflections in a glass of water

I've noticed that if you take a full glass of water and look from above, through the water, you can't see through the glass sides - instead, you see a reflection. I tried with a laser pointer and the ...
1
vote
1answer
190 views

Simple Question: Speed of Electromagnetic Waves in a Medium

If the speed of an electromagnetic wave in a particular medium is such that $v = c$, the speed of light, does this mean that the permeability $\mu = \mu_0$, i.e. that of a vacuum and the index of ...
2
votes
1answer
102 views

Perfectly focusing refractive surface

On reading Feynman's lecture on physics, in the geometrical optics section he said that a curve which focuses all the rays coming from a point to another fixed point beyond the refracting surface ...
2
votes
2answers
98 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
259 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 $d_i = - \frac{n_2}{n_1} d_o$
4
votes
2answers
419 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
101 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
365 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
18 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
323 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
638 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
287 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 ...
6
votes
2answers
651 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
326 views

Difference in velocity of light in change in medium [duplicate]

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
89 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 ...