Tagged Questions
0
votes
0answers
32 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 ...
0
votes
1answer
27 views
Phasor representation of voltage in frequency domain
In a text on application of electromagnetism in transmission line, there introduces a phasor for the voltage (in frequency domain)
$$\tilde{V}(x) = V^+e^{-i\beta x} + V^-e^{i\beta x.}$$
Here $V^+$ ...
1
vote
0answers
46 views
Longitudinal EMAG wave?
I'm reading about optical waveguide analysis, and often come across the terms "transverse electric mode" vs. "transverse magnetic mode". As I unerstand, it means that the electric/magnetic field has ...
1
vote
0answers
47 views
Fourier Transform of ribbon's beam Electric Field
I have a monochromatic ribbon beam with $E(x)e^{i(kz-\omega t)}$ being the electric field's amplitude. I want to show that the lowest order approximation in terms of plane waves is
...
3
votes
1answer
73 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 ...
7
votes
2answers
222 views
Can light waves cause beats?
My question is pretty brief. When two sound waves of nearly same frequencies interfere, we get beats.
But, I have not observed something like that happening in the case of light. In fact, most of the ...
1
vote
1answer
86 views
Eikonal approximation for wave optics. Why follow the unit vector parallel to the Pointing vector?
The description of the passage from wave optics to geometrical optics claims that light rays are the integral curves of a certain vector field (the Pointing vector direction, normalized to 1). Here ...
1
vote
2answers
188 views
What is light, and how can it travel in a vacuum forever in all directions at once without a medium?
I know there are many questions that are similar (maybe identical?). I am not a physicist nor a student - I am just interested in physics and have been watching many physics channels on youtube ...
-1
votes
1answer
68 views
Signal emission and detection with certain parameters; Electrical Engineering [closed]
Could a micro-transmittting device, smaller than, say, a golf ball be employed to emit an ultra-narrow detectable beam, (e.g. 1mm) with range of one or 1.5 decimeter to 2 or less centimeter? The ...
14
votes
3answers
735 views
Amplitude of an electromagnetic wave containing a single photon
Given a light pulse in vacuum containing a single photon with an energy $E=h\nu$, what is the peak value of the electric / magnetic field?
3
votes
1answer
552 views
Phase and Group Velocity of Electromagnetic Waves
Moving charges produce oscillating electric and magnetic fields -we have an electromagnetic wave.
In terms of moving charges or at the level of charges, what is phase velocity and group velocity of ...
3
votes
1answer
159 views
Does $\lambda\nu = c$ hold for all the waves in the universe?
Are all waves in the universe the same as electromagnetic waves?
Basically, my question arises from an equation I found in my chemistry textbook:
$$\lambda \nu ~=~ c.$$
This states that the ...
0
votes
0answers
42 views
EM-wave hits a brick-wall, $\pi/2$ -phase-shift? [duplicate]
Possible Duplicate:
Phase shift of 180 degrees on reflection from optically denser medium
If I have a cord-wave, I get a phase-shift with attached cord but do I get such a phase-shift with ...
0
votes
2answers
170 views
Counting electromagnetic modes in a rectangular cavity and boundary conditions
The electric field in a cubical cavity of side length $L$ with perfectly conducting walls is
$E_x = E_1 \cos(n_1 x \pi/L) \sin(n_2 y \pi/L) \sin(n_3 z \pi/L) \sin(\omega t)$
$E_y = E_2 \sin(n_1 x ...
2
votes
2answers
106 views
What is the history behind the factors of 3 in the classification of electromagnetic radiation?
What is the history behind the factors of 3 in the classification of electromagnetic radiation?
See e.g. http://en.wikipedia.org/wiki/Radio_spectrum#By_frequency
Is this (just) inherited from the ...
1
vote
2answers
74 views
What is difference between the miltary radar in 1940's from commercial antenna that is for the use of TV
What is difference between the miltary radar in 1940's from commercial antenna that is for the use of TV?
I have read article from some of the WW2 history website that call the German radar the ...
3
votes
2answers
595 views
How do mirrors work?
Apparently, light is just a certain wavelength, or "the visible spectrum" of electromagnetic waves. If I recall correctly, my physics teacher explained to me that electromagnetic waves are basically ...
9
votes
1answer
96 views
Wave Physics - can a dynamic waveform be constrained to a specific geometry by signal processing alone?
Suppose that you have a signal source, a set of point-transducers, and a handful of moderately powerful DSPs. Is it possible to construct an arrangement of the transducers such that the original ...
1
vote
1answer
321 views
Relationship between classical electromagnetic wave frequency and quantum wave function + de broglie frequency
As it is.
As I study through classical mechanics and quantum mechanics, I began to wonder whether there is a relationship between classical electromagnetic wave frequency and quantum wave function ...
7
votes
3answers
3k views
Phase shift of 180 degrees on reflection from optically denser medium
Can anyone please provide an intuitive explanation of why phase shift of 180 degrees occurs in the Electric Field of a EM wave,when reflected from an optically denser medium?
I tried searching for it ...
1
vote
2answers
591 views
Producing photons with same frequency, different amplitude wave
I don't understand how two photons of the same frequency can have different amplitudes, neither how to produce them.
I know that classically the square of the amplitude is proportional to the energy, ...
3
votes
2answers
952 views
The energy of an electromagnetic wave
The intensity of an electromagnetic wave is only related to its amplitude $E^2$ and not its frequency. A photon has the same wavelength as the wave that's carrying it, and its energy is $h f$.
So ...
-1
votes
2answers
184 views
Why do you get electric field of a light wave?
Why do you get electric field of a light wave in following form: $E(x,t)=A cos(kx-\omega t- \theta)$?( look at: https://public.me.com/ricktrebino -> OpticsI-02-Waves-Fields.ppt, p. 18)
9
votes
5answers
511 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 ...
5
votes
5answers
1k views
Why no longitudinal electromagnetic waves?
According to wikipedia and other sources, there are no longitudinal electromagnetic waves in free space. I'm wondering why not.
Consider an oscillating charged particle as a source of EM waves. Say ...
1
vote
3answers
388 views
Is it correct to say that electromagnetic waves does not require a medium?
I can conceive of a particle existing in empty spacetime, but not a wave. A wave appears to me at least, to insist upon a medium for its very definition.
I understand that the 19C physicists ...
0
votes
0answers
112 views
What is the electric field part of an EM wave? Radiation field or the induction field?
Look at this image:
I wonder if the electric field is from the induction field from a vibrating electron or the radiation field? If it is from the radiation field, as I suppose, than can someone ...
2
votes
3answers
451 views
Electromagnetic wave reflection vs. light reflection
Related: x-ray interaction with atmosphere
I know that electromagnetic waves of particular frequencies reflect from the ionosphere. And the light (which from one perspective is an electromagnetic ...
2
votes
2answers
180 views
Does EM radiation (any, i.e. RF), or sound, radiate everywhere at once?
I am having trouble understanding electromagnetic radiation (or waves in general, be it EM or sound). If I have a 1 Watt speaker, is it infinitely divided and spread out so that everyone in every ...
7
votes
3answers
814 views
Why is it necessary for an object to have a bigger size than the wavelength of light in order for us to see it?
I keep hearing this rule that an object must have a bigger size than the wavelength of light in order for us to see it, and though I don't have any professional relationship with physics, I want to ...
0
votes
1answer
256 views
Speed of Light, Photons or WaveSpeed?
The speed of light is almost 300 000 km/s.
The photons have a speed along the wave, and the wave have a speed straight forwards.
What is the speed of light? Is it the speed the photons have along ...
5
votes
5answers
972 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 ...
1
vote
1answer
128 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 ...
3
votes
2answers
210 views
Waveguide and ethernet
I am having a doubt about waveguides and the traditional Ethernet cable.
The newest Ethernet i.e. the 10Gbps Ethernet has an astounding speed of 10Gbps. Which consists of 4 lanes in Cu as physical ...
3
votes
1answer
731 views
Light waves and Schrödinger probability waves
Ok, bearing in mind that I only have a brief understanding of quantum mechanics (no formal education, only from reading about concepts in books), so I could be way off here, I have a question ...
1
vote
0answers
341 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 ...
-2
votes
3answers
704 views
Electro Magnetic Waves can cause matter displacement?
After watching this video:
http://www.youtube.com/watch?v=j1jIjx0XF_U
The experience is made with a speaker that generates a sound wave or mechanic wave. Can you use this to establish a link to ...
3
votes
2answers
1k views
How is the speed of light calculated?
How is the speed of light calculated? My knowledge of physics is limited to how much I studied till high school. One way that comes to my mind is: if we throw light from one point to another (of known ...
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 ...
1
vote
2answers
217 views
Creation of the Electromagnetic Spectrum [closed]
After seeing this image:
http://mynasadata.larc.nasa.gov/images/EM_Spectrum3-new.jpg
And reading this:
"The long wavelength limit is the size of the universe itself, while it is thought that the ...
