Tagged Questions
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0answers
39 views
Historical aspect of wave theory of light
Huygens thought light as a wave. Wave is a propagation of physical disturbance. We now know that light is electromagnetic field. Electric and magnetic field fluctuates here. What Huygens really ...
5
votes
2answers
94 views
If light rays obey to the wave equation, why can they be thought as straight lines?
I'm a newbie with physics but I'm wondering how a ray of light can essentially be represented. I have always known that a ray of light proceeds in a straight line until it encounters another object ...
30
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5answers
4k views
Why doesn't light kill me?
I was attending my philosophy class and in the middle of student presentations, I found myself mentally wondering off and thinking about light. After a few minutes of trying to piece together how the ...
3
votes
2answers
83 views
Is light's path a wave?
In a lot of textbooks I see a schematic of light drawn as a squiggly line. I have even heard that some things are too small to be seen because they are smaller than the wavelength of light (and ...
3
votes
1answer
77 views
Can you “fold” EM or light waves? (i.e) long wave that is reflected by mirror in fragments - like in the game “Snake”
So, I was reading about the Casimir effect. Two mirrors facing each other attract to each other in a vacuum. The reason is due to pressure exerted on those mirrors from the multitude of EM waves (like ...
2
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3answers
223 views
If photons can be absorbed by electrons, wouldn't that mean light has a charge? [duplicate]
I am a biochemistry and molecular biology major. If photons can be absorbed by electrons, wouldn't that mean light has a charge? Electrons only attract positive charges. Isn't it?
1
vote
1answer
37 views
william herschel discovering infrared problem
when william herschel conducted the experiment of separating white light with a prism and measuring the different colors, he put a thermometer past the red color as a control finding it to pick up the ...
4
votes
2answers
195 views
How photons represent colors that you see?
Right now, my understanding is that, a mixture of photons of many different frequencies is perceived as white by your eye. While no photons at all, is perceived as black. And photons with the blue ...
1
vote
3answers
41 views
Trapping EM radiation
Is there a material which can allow light (or any other EM radiation) to pass through from one side as if it is transparent but its other side reflects light like a mirror?
1
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2answers
111 views
Do photons actually generate a slight kinetic force?
My question is even though photons have no (rest) mass, do they emit a external force due to EM radiation causing electrons to be excited and jump to higher energy shells which electrons have mass ...
0
votes
1answer
119 views
The nature of light
I'm not sure if this has been answered before, but I figured this would be the right forum to find out. I'm not by any means an expert in physics, just someone who's interested in understanding more ...
0
votes
2answers
260 views
EM waves: How do they travel for billions of km without damping
If a star is 1 billion light years away, it means that the light we see from the star is emmitted billions of years ago.
How does this light not undergo a frequency change or get damped inspite of ...
0
votes
2answers
260 views
Young's Double Slit experiment question
Q-A beam of light consisting of two wavelenghts 600 nm and 450 nm is used to obtain interference in Young's Double Slit experiment (YDSE). Find the least distance from the central maximum where the ...
2
votes
1answer
100 views
Commercial Infrared lights
I purchased an infrared light. It's a 100 W Philips infrared lightbulb. Says it's infrared, but I haven't done any spectrum analysis so I don't know for sure if it's just red or really infrared.
As I ...
0
votes
3answers
486 views
Intensity of light
If we have 2 beams of light with equal intensities, but with different frequencies, wouldn't the one with the higher frequency generate more power?
If so, how come the intensity, which is in $W/m^2$, ...
2
votes
3answers
814 views
Is there something special in the visible part of electromagnetic spectrum?
I always wondered how much information we get from color. Things we see have different colors; edible products change color when began to spoil so we have a notion what color a fresh product should ...
15
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11answers
4k views
Why is light called an 'electromagnetic wave' if it's neither electric nor magnetic?
How can light be called electromagnetic if it doesn't appear to be electric nor magnetic?
If I go out to the sunlight, magnets aren't affected (or don't seem to be). And there is no transfer of ...
0
votes
3answers
71 views
What kind of “camera” and “light” source should I use to detect the path along which the light moves?
I would like to have an image ( in any kind of space ), where I see the path of a "light" source. In my understanding the most common, directed source would be a laser pointer.
...
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0answers
52 views
Electromagnetic charge [duplicate]
Possible Duplicate:
If electromagnetic field give charge to particles, does photon carry charge?
Is it possible to charge photons
I was wondering if light when it's in wave form (seeing ...
2
votes
2answers
340 views
What's the Significance of Color Changes Between EM-Spectrums?
As everybody knows that Black objects are black because almost all the light that falls on them is absorbed into the material. Little or no light is reflected back toward our eyes, therefore we see ...
6
votes
5answers
814 views
Why is Light invisible?
Why can't we see light? The thing which makes everything visible is itself invisible. Why is it so?
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2answers
84 views
Painting wine botles
Yes, it's a physics related question. Read on.
I know from general knowledge that in order to produce a decent wine, you must keep it in a dark place. Therefore, from my knowledge of physics I guess ...
1
vote
2answers
158 views
PV cell for invisible spectrum only
Is it possible to make a photovoltaic cell that would only absorb the invisible part of the electromagnetic spectrum, while letting visible light pass through or bounce off its surface?
I guess that ...
9
votes
5answers
534 views
Superposition of electromagnetic waves
The superposition of two waves is given by
$$\sin(\omega_1 t)+\sin(\omega_2 t)=2\cos\left(\frac{\omega_1-\omega_2}{2}t\right)\sin\left(\frac{\omega_1+\omega_2}{2}t\right).$$
For sound waves, this ...
2
votes
2answers
99 views
Luminescence when ripping (answered) and when pouring (not answered)
As a father to a small child, I have often observed this phenomenon but have until i posted this question not found the vocabulary to Google for it.
Can you explain what I am seeing?
In a darkened ...
0
votes
1answer
71 views
What is the new distance for resolution of the images? [closed]
The taillights of an automobile are $1.25\:\rm{m}$ apart. Assume the pupil of a person's eye has a diameter of $5\:\rm{mm}$ and the light has an average wavelength of $604\:\rm{mm}$. At night, on a ...
3
votes
2answers
476 views
Are Colors Emitted at Specific Temperatures?
There are quite a few nagging questions I have been having over the years, I do not require a full explanation, just some guidance in my assumptions and pointers if I am very wrong.
My basic ...
4
votes
5answers
992 views
How many colors exist?
How many "colors" do exist?
Our perception:
As far as I know, colors are just different frequencies of light. According to wikipedia, we can see wavelengths from about 380 nm und 740 nm. This means ...
5
votes
2answers
190 views
Does light escape when I open my blinds?
When I open my blinds, there is light enough to read a book outside while the lamp is on inside.
So when I close my blinds, does the light that otherwise will escape, stay inside and thus being ...
5
votes
5answers
1k views
How to Make RF Waves Visible
I understand RF (Radio Frequency) Waves are electromagnetic waves and a mode of communication for wireless technologies, such as cordless phones, radar, ham radio, GPS, and television broadcasts. Most ...
3
votes
1answer
410 views
Formula for polarized “light” transmission through close filters?
I'm still trying to understand photons (or polarized electromagnetic radiation).
This question is similar to one of my previous questions, but different:
Consider the famous demonstration of crossed ...
1
vote
1answer
134 views
How colored light can be explained if light is considered as emission of photon?
If light is considered as wave, then different colored light can be explained as waves of different wavelength/frequency. How colored light can be explained if light is considered as emission of ...
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
2answers
162 views
Is there a reason for photodynamic therapy to not cause cancer if mobile phones might?
I don't want to open a debate about whether cell phones can cause cancer,
I read the thread: Could cell-phone radiation cause cancer?
For the sake of this question let's assume there's a chance for ...
0
votes
2answers
271 views
Do and can phone signals come inside AC car which is glass-packed
Can phone signals penetrate glass, so can I expect phone signals to come if I am sitting inside a closed AC car.
Thanks,
2
votes
3answers
1k views
UV reflective surfaces
Do surfaces that reflect visible light efficiently also reflect UV light? If not, are there surfaces that do?
(I have a large array of UV LEDs that I need to make larger and more diffuse, so I'm ...
1
vote
0answers
344 views
Double Slit Problem, Waves and Optics [closed]
Given d(slit separation)= $0.158\:\rm{mm}$, $\lambda _{red}= 665\:\rm{nm}$, $\lambda _{g/y}= 565nm$, L(distance from screen)= $2.24\:\rm{m}$
What is the distance between the third order red and ...
14
votes
4answers
4k views
Why glass is transparent?
Once I asked this question from my teacher and he replied "because it passes light", "and why it passes light" I asked and he said "because it is transparent".
Same question again, Why glass is ...
17
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3answers
2k views
8
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5answers
908 views
What happens to light after it enters an eye
What happens to the light [energy] after it enters an eye and hits the rods and cones? I presume the energy becomes electrical, and it must be near 100% perfect, else our eyes would heat up? Or am I ...
