0
votes
2answers
61 views

How does the human eye knows how far the object from which the photon was reflected?

A photon is emitted from a source and reflected off an object (or objects) until it hits the human eye. The color of the object we see depends on the photon wavelength. If photon travels with constant ...
2
votes
3answers
79 views

What happens to photons after they hit objects?

If I am not wrong when light hits for example white wall most of the photons are absorbed and transformed into heat and few of the photons at certain wavelength are reflected from the object. So white ...
1
vote
0answers
13 views

What are the factors affecting transparency and color of a substance [duplicate]

What is the reason behind visual properties like color and transparency of different substances? I have always heard that the structure of the substance is responsible for these properties. I always ...
1
vote
1answer
74 views

Do photons change velocity instantaneously?

Any object traveling at c is observed as traveling at c in all reference frames. When a photon travels through a vacuum at c, all reference frames observe it traveling at c. When a photon passes ...
0
votes
2answers
245 views

Energy & Mass of a Photon [duplicate]

$$\text{Please read the whole question before answering}$$ Before I ask my question, I would like to say that "Yes, I do know a photon has no mass." I was helping someone here on P.SE with the ...
1
vote
1answer
51 views

Photons “rate of fire”

I'm not sure if this makes any sense but, do photons "discharge" from a source at an infinite rate?
2
votes
4answers
118 views

Photons to Represent a Wave

I fear that I have a fundamental misconception about the "wave particle duality" of light, but in a related question, the answerer said, in some sense, that a light wave propagates until it hits ...
1
vote
1answer
43 views

Can a single photon be polarized non-linearly?

I want to check if I correctly understand polarization. Considering a single photon travelling in vacuum, it can only be polarized linearly under the same direction at any time, right? When we talk ...
1
vote
0answers
33 views

Is there any acceleration of light? [duplicate]

I find it hard to believe that photons always travel with 3 x 10^8 m/s just from the start. But there must be some acceleration of light. Maybe huge or taking place in picoseconds. So what maybe the ...
0
votes
2answers
68 views

Faraday Effect does light bend or lose energy?

I was reading upon Faraday effect when it said Faraday effect causes a rotation of the plane of polarization That in mind, does this mean the light can be bent around or does the light loose ...
4
votes
1answer
96 views

If I'm running away from chasing gamma photons, I can see them, right?

Suppose Bruce Banner goes back in time, convinced that the Hulk is a stupid menace. Let's say he also borrows Quicksilver's speed abilities (maybe the Flash is more appropriate, but based on the ...
1
vote
3answers
109 views

Can light be trapped theoretically?

My question is a little silly I know, but I'm curious to know if a particle of light can be theoretically trapped between two reflective screens. For example once the particle of light has left it's ...
4
votes
2answers
494 views

Do x-rays and gamma rays also contain photons like visible light does?

Do x-rays and gamma rays also contain photons like visible light does? If so, then what makes photons of visible light and other waves different? The rest mass of a photon is zero, but as it moves at ...
2
votes
1answer
113 views

Why do i see bright red hand when i place flashlight behind my hand?

When I place a working flashlight behind my hand, I see my hand bright red because of the light. So my question is, why do I only see red light after transmission even if incoming light from the ...
3
votes
4answers
579 views

What is difference between white objects and transparent objects as far as photons are concerned?

Transparent materials let photons through because the energy gap of electron is so large that the photons cannot be absorbed. If the material absorbs a photon, the photon disappears; does this mean ...
0
votes
1answer
67 views

relation between photon number and energy

Suppose there are two light beams. One is red while the other is violet. The energy of both is the same. Which one of these beams has a larger number of photons, or is the number of photons relevant? ...
2
votes
1answer
62 views

Light Waves and Light Photons gedanken Experiment

Suppose you have a source of light that emits light with a wavelength of 2 meters, and you set the device to be turned on and switched off alternately. You also set it so that each interval the device ...
2
votes
1answer
121 views

When photons are emitted, do they accelerate to reach the speed of light? [duplicate]

Photons are considered mass-less particle with a specific velocity but according to the electromagnetic theory, a photon is considered to have both energy and momentum. So what happen when they are ...
0
votes
2answers
246 views

What is the difference between light and visible light? [duplicate]

After watching a few videos on light and electromagnetic radiation, I am a little confused. The way things are explained, is that light is just the same as electromagnetic radiation I thought this ...
1
vote
3answers
128 views

About the speed of light and gravity

I read (I think ) that part of relativity theory is that a strong gravitational field distorts the uniform passage of time. If this is true and a lightwave 'travelling' to Earth passes a star near ...
17
votes
5answers
2k views

When photons reach us, what exactly is happening to us and to that photon?

I'm new to physics and am just going through some of the free online classes at World Science U, and after watching this video on the nature of the speed of light and its constancy, a question came to ...
1
vote
3answers
136 views

Do atoms of a surface excite to reflect the light?

How do surfaces reflect certain colours and absorb the others?
2
votes
3answers
123 views

Why can colors be mixed? [duplicate]

We can combine colored light, creating other colors, at least in terms of visual perception. But how it the result physically "a different color" - if it is at all? Or is all this not a physical ...
0
votes
0answers
92 views

Photons and Black holes

How many photons in one Planck volume would it take to form a tiny black hole? A photon doesn't have mass but it does have energy, $1.0101 \times 10^{-37}$ Joule for red $650$ nm wavelength light if ...
0
votes
2answers
56 views

How is the image in a mirror created? Are there infinitely many light rays?

How is the image in a mirror created? Are there infinitely many light rays? My motivation for the question is from image processing. We work with images as discrete 2D functions, as matrices. Spatial ...
0
votes
2answers
121 views

Can relativistic momentum (photons) be used as propulsion for 'free' after the initial generation?

In discussing this question about propelling a spacecraft with photons and their relativistic momentum, the author asked that I restate my comment as another question. If photons can really be used ...
2
votes
1answer
131 views

Is every electromagnetic radiation considered “light”?

Somebody mentioned on Freenode chatroom for physics that All Electromagnetic Radiation are delivered in form of Photons not just light. Is it true? Does that mean if we get a THF electrical ...
1
vote
3answers
68 views

Does a high energy photon experience deceleration or direction-change when it impinge into water or something due to the change of refraction index?

Wave experiences refraction when it propagates into another medium which has different refraction index. Lights surely does experience refraction at the border of mediums which have different ...
0
votes
0answers
36 views

How do cathode ray tubes (CRT) synthesize colours?

I just read about how LCD displays were based only on black&white contrasts, and only colour filters on each subpixel generated the colour of a pixel. However, how does that happen for a CRT? Is ...
1
vote
3answers
124 views

Intuitive understanding of wavelength

Light is described as having wavelength. I can somewhat understand this in connection with for example the double slit experiment, that photons interact spatially in a wave like manner. But can the ...
4
votes
0answers
73 views

Optical Bloch Oscillation

I have a doubt about how the optical Bloch oscillations happen in a 1D photonic crystal. I try to explain: in a photonic crystal with discrete translational symmetry in one direction I superimpose a ...
-1
votes
1answer
108 views

Can a wave exist on the “face” of a wave?

It would seem that this would be possible with waves in water. What about other waves Clarification: Given a wave starting from a point of impact, in water, at: Time 0:00 and xyz 0,0,0 and the ...
2
votes
0answers
136 views

If photons don't have mass, how can they accelerate objects? [duplicate]

As far as I know photons don't have mass but they do have momentum ($p=mv$). Scientists say that if we put a shiny (reflective) shield of large radius in the vacuum of space, then light from sun will ...
3
votes
2answers
109 views

The speed of light as it approaches a massive body

No matter how fast you go, you will aways perceive the speed of light as constant. Taking that as a fact, the special relativity theory was formulated. Now, for what I understand about general ...
1
vote
3answers
143 views

How far does a Photon's field Extend?

I read the related answer to whether photons have size, and the answer seemed to be it depends. If a Photon, or a rather an E&M wave has a magnetic and electric field, should things be able to ...
2
votes
2answers
189 views

Can we observe diffraction even if the slit size is tending to zero?

According to Huygens principle, if we consider any point of the primary wave fronts, each point is the source of secondary disturbance. If the point size we consider tends to zero, the number of ...
3
votes
2answers
158 views

What is the energy distribution of light if it has an infinite length?

What is the energy distribution of light if it has an infinite length? I have read in one of the answers here on phys.SE that light has actually an infinite length. But then what is the energy ...
3
votes
1answer
107 views

Polarisation of light is a wave concept or applicable to photons as well?

I have a very fundamental question. We explain polarisation of light assuming wave nature of light. Is it still valid if we assume light as photons? Or in other words, polarisation is a wave concept ...
3
votes
1answer
640 views

Didn't Newton's Corpuscular theory fail to explain reflection?

In 1637 Descartes gave the corpuscular model of light and derived Snell's law. This Corpuscular model of light was further developed by Isaac Newton in his famous book entitled OPTICKS and because of ...
2
votes
3answers
108 views

How to smooth the spectrum of a light source?

Could somebody please tell me if there's a reasonably cheap substance or device can I use to smooth the spectrum of a light source? For example, if the spectrum has spikes as in the blue graph below, ...
0
votes
0answers
29 views

Light pulses and energy-time uncertainty principle [duplicate]

Suppose we have a monochromatic light beam. We put an obstacle between source and observer and remove it repeatedly by certain frequency such that observer sees an oscillating intensity of light. Will ...
1
vote
1answer
121 views

What gives substances their color?

As far as i know (i may be wrong!), substances appear to have a definite color because they reflect/ transmit all the light rays of the given color, and absorb all the lights rays of the remaining ...
40
votes
6answers
2k views

Photons from stars--how do they fill in such large angular distances?

It would seem that far-away stars are at such a distance that I should be able to take a step to the side and not have the star's photons hit my eye. How do stars release so many photons to fill in ...
0
votes
1answer
130 views

Concentration of photons: How many can you slow down in a given unit of space?

Being able to slow down light to the speed of a bicicle as shown in this vid: http://www.youtube.com/watch?v=EK6HxdUQm5s Led to a question: Given a unit of space e.g. 1cm^3, and then you slowed down ...
3
votes
1answer
64 views

How far can diffused undersea light travel and still be perceived by the human eye?

Example: If one SCUBA diver looks past another SCUBA diver horizontally into negative space, how far away is the most distant emission of 'blue' light waves? Consider the sight angle in question to ...
1
vote
0answers
63 views

Is there spatial data loss in light passing through transparent crystal?

There is perfect parallelepipedal bar made of transparent crystal with cubic lattice floating in vacuum. Faces of parallelepiped are parallel to lattice axis. There is image, forming checkerboard ...
6
votes
3answers
216 views

Can visible light be emitted from a non-thermal source?

I was reading about thermal and non-thermal radiation and I was wondering if visible light can be emitted from a non-thermal source?
6
votes
2answers
828 views

Slowing down light in an opaque crystal for a whole minute

I just read about a team of physicists at the University of Darmstadt, Germany, that managed to completely slow down a beam of light that traveled through an opaque crystal (article here). How is it ...
-4
votes
1answer
155 views

how can u split the Photon? [closed]

If any equations are there ,for split the light particle, means that i have a 1m length of light just consider that in that who can i split the light particle into 1/2 m length Pls tell
1
vote
2answers
136 views

Is it possible for a photon to be at rest? [duplicate]

I know it doesn't really make sense if looking at the photon from the wave point of view, but is there any law of physics which prohibits a photon from stopping completely? Thanks.