Stack Exchange Network

Stack Exchange network consists of 174 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [electromagnetic-radiation]

Propagating solutions to Maxwell’s equations in classical electromagnetism and real photons in quantum electrodynamics. A superset of thermal-radiation.

0
votes
2answers
59 views

Another objection to Feynman's moving infinite sheet of charge “radiator”

In The Feynman Lectures on Physics Vol II 18-4, A travelling field we are provided the thought experiment of two uniformly and oppositely electrically charged planar sheets of infinite extent lying in ...
5
votes
0answers
62 views

Consider two electrons released from rest at a distance $d$. How much energy is radiated?

Abraham-Lorentz? Two electrons d apart have potential energy. Release them, they will be repelled according to Coulomb's law. I could make an assumption about the associated vector potential, but I ...
0
votes
2answers
25 views

Magnetic field and magnetic forces and polarity

When the polarity of the voltage applied to a dc motor is reversed, the direction of motion does not reversed. Why not? How could the direction of motion be reversed?
0
votes
0answers
18 views

Magnetic field and magnetic forces

Hall-effect voltages are muchh larger for relatively poor conductors (such as germanium) than for good conductors (such as copper), for compatible currents, fields, and dimensions. Why?
-1
votes
0answers
19 views

Creating magnetic field [on hold]

I read this article yesterday about creating super strong magnetic fields with lasers https://physicsworld.com/a/radiation-friction-could-make-huge-magnetic-fields-with-lasers/ But was disappointed ...
0
votes
1answer
33 views

Frequency gap between neighbouring spectral lines

According to classical theory the atomic line spectra are discrete and their frequencies quantized. Have the newer quantum theories changed anything since then, giving some other expressions for the ...
0
votes
1answer
48 views

Magnetic forces in physics

Could an accelerator be built in which all forces on the particles, for steering and for increasing speed, are magnetic forces? Why or Why not?
0
votes
0answers
29 views

Magnetic force and field involving simple harmonic motion

Is there a simple harmonic motion when the electromagnetic compass was made by suspending a coil. The coil align itself perpendicular to the horizontal components of the earth's magnetic field and ...
0
votes
0answers
19 views

Can electromagnetic radiation affect the ability to navigate using magnetic field of Earth?

Recently I came several articles how Electromagnetic Radiation (EMR) is leading to a decline in the population of bees and birds. The important point being emphasised is that EMR affects their ...
0
votes
0answers
12 views

Should I account for reflection of electromagnetic waves in a signal strength simulation for household use? [on hold]

I'm currently working on my bachelors thesis, which is about designing a software that allows users to model signal strength for transmitting and receiving signals (router/computer as easiest example) ...
5
votes
0answers
44 views

Do radio beams self-focus in the interstellar medium?

Summary: In a plasma, electromagnetic waves create a ponderomotive force that pushes electrons and ions out of the way. Thus, in an intense laser beam, electrons tends to move away from the areas ...
3
votes
1answer
56 views

Does the human brain emit ULF waves?

In the book The Electric Universe by David Bodanis, the author writes that "invisible waves stream out of from our brains with a wavelength of about 200 miles". Is it true that the brain produces ULF ...
5
votes
2answers
84 views

Would spinning salt emit radiation?

It wouldn't need to be salt. Basically I was initially thinking about a mechanical transmitter, essentially just taking two equal opposite charges and fixing them to the opposite ends of a pole. ...
1
vote
1answer
37 views

Like Gamma ray is made of the helium atom, X- rays are made of accelerated charged particles, what are the other radiation in EM spectrum made of? [closed]

I just want to know what are microwaves and radio waves made up of, when they travel through vacuum what is it that causes electric and magnetic field vibration.
0
votes
2answers
60 views

Are photons and electromagnetic waves the same thing? [duplicate]

I have a little bit of confusion: From my understanding (which could be totally wrong), photons are the same as electromagnetic waves but are called photons because their frequency is in the realm of ...
-2
votes
0answers
16 views

Normal incidence at a plane dielectric boundary [closed]

How to prove that for glass air interface ($n_2=1.5$ ,$n_1=1.0$) for normal incidence of EM wave reflection and transmission coefficients are $0.04$ and $0.96$?
-1
votes
0answers
23 views

Question on dipole radiators

Two dipole oscillators are situated with their centres in the same horizontal plane as the detector and the line of vibration is vertical. If oscillators are 1/4 wavelength apart and are 90 degrees ...
-1
votes
1answer
43 views

Why can't ultraviolet light pass through glass?

What factor determine whether a body behaves like a transparent object for EM waves of a particular frequency?
0
votes
1answer
21 views

Are the bandwidths of a laser pointer and a sodium-vapor lamp comparable?

The question is not about the slightly differing wavelength of the devices caused by manufacturing processes or the shift from changing temperature. A German source says that the spectral width with ...
1
vote
0answers
18 views

Analytical Solution: EM Scattering from Hemispherical Indentation in Plane

I have a problem of trying to calculate the losses that occur when a beam of light reflects from the surface of a partially transparent medium that has an open cavity. The circumference of the cavity ...
5
votes
3answers
48 views

Common microwave absorbing substances

I'm looking to demonstrate to class of students how microwave absorption works, but I need something relatively common which I can easily make into a board. Does anyone have any suggestions for ...
1
vote
1answer
60 views

The function of the pinhole in the double slit experiment

Even with incoherent light from the sun and not having any laser, Young achieves a result by reducing the incident light to a point-like source. This makes sense because a wider beam works like many ...
1
vote
1answer
29 views

Electric force between two parallel plates one of which got a rough surface

So if I have two parallel metal sheets separated by 0.1 meters with air as a dielectric with a breakdown strength of 3MV/m and I'm applying a voltage pulse that goes from 0 to 100kV in few ...
33
votes
2answers
2k views

Can light be compressed?

What if we take a cylindrical vessel with an inside surface completely reflecting and attach a piston such that it is also reflecting. What will happen to light if we compress it like this?
0
votes
2answers
56 views

Double slit experiment- light intensity

The standard explanation for the interference pattern is one of constructive and destructive interference between the light waves from the two slits. But, am I right in thinking that light intensity ...
0
votes
1answer
36 views

Do gravitational wave produce varying electromagnetic waves? [closed]

When gravitational waves produce electromagnetic waves, do they produce them of the same frequency or of varying wavelength?
3
votes
1answer
108 views

What, explicitly, happens as EM radiation travels from A to B?

I'm in my fourth year of a Masters Physics course, and am quite concerned that I don't fully understand this. Suppose a photon is emitted at point A and absorbed at point B one light-minute away. We '...
-2
votes
1answer
19 views

Material for lid of a solar cooker

Normal glass allows visible light to pass through, but it blocks ultraviolet rays. If I use a glass which allows both the kinds of rays to pass through it as the lid of my solar cooker as lid, will ...
5
votes
1answer
52 views

Relation between radio waves and photons generated by a classical current

Several questions have been posted on Physics SE regarding the relationship between photons and electromagnetic waves, and several good answers have been given. Some of those questions are listed ...
2
votes
3answers
82 views

Could a microwave oven be tuned to defrost well? [closed]

Typical microwave ovens do a lousy job of defrosting because liquid water absorbs their radiation far better than ice. So once a spot melts, it will quickly rise to cooking temperature while the rest ...
0
votes
0answers
40 views

Electric field produced by oscillating charge

In Feynman Lectures on Physics, Volume 1, Chapter 29 he proves that electric field propagates like a wave. My attempt is like this:- I don't know latex therefore I'm posting the image But to prove ...
-1
votes
2answers
98 views

How can the quanta of electromagnetism be photons if they have no mass? [closed]

I thought charge only existed when mass was present. Does this mean String Theory hypothesizes photons having charge?
1
vote
1answer
26 views

Physical significance of growth rate in plasma

Let us say that we have a dispersion relation curve and associated instability curve as shown below for a magnetised plasma, which have been formulated through kinetic theory. The frequencies and ...
1
vote
0answers
23 views

Do all accelerating charge emit EM radiation? [duplicate]

A nucleus and an electron attract each other, so if they are to remain apart, the energy of the electron’s movement must balance the energy of attraction. However, the laws of physics had previously ...
16
votes
5answers
5k views

Do Maxwell's equations predict the speed of light exactly?

I know that $\frac{1}{\sqrt{\mu_0\varepsilon_0}}$ is equal to the speed of light but is this prediction accurate? I mean is it 100 percent accurate?
0
votes
1answer
32 views

Microwave cooking

This is just a little curiosity I've had, and I wonder what y'all think: I am poaching a chicken egg in a small (about 4 in. diameter) glass dish in my microwave. Let's assume the microwave is set on ...
0
votes
1answer
48 views

How do magnets move towards or away from each other?(Explanation on a molecular level)

Imagine two magnets on a horizontal surface, with two opposite poles facing each other. If one of them is north, then the other magnet with the south pole facing the north will move towards the north ...
0
votes
0answers
9 views

Propagating degenerate modes in circular waveguide

I need to develope a tool that asks how many modes I want let propagate inside a circular waveguide with radius a. At this level I compute inside a few zeros of ...
1
vote
2answers
34 views

How does the energy of a solar flare propagate?

Does it radiate outward, spherically, or is it more directed? Is there some opening angle? Is it more complex than this?
2
votes
2answers
102 views

How to tie in black body radiation with quantum theory?

I'm having trouble understanding the physical basis for the UV catastrophe in blackbody radiation graphs. Is the source of the drop off past UV because the electrons in a blackbody substance can't ...
1
vote
0answers
17 views

Behaviour of photons in different materials

Often when learning about heat transfer within metals and thermal conductors,the heat transfer is explained by saying how molecules vibrate in thier positions to conduct heat. But if that's the case ...
0
votes
2answers
42 views

Understanding the Interference of Light

I would like to understand interference using 2 illustrations: 1) Bulbs send out light in all directions, right? If so, at a particular instant of time, shouldn't all the light waves coming out from ...
0
votes
1answer
22 views

Magnetic Shielding

Imagine a substance in an electric field. You don't want the electric field to interact with the object you have put in its way. What should be the type of material this magnet should be made of to ...
1
vote
1answer
136 views

Does a photon require an EM field to exist?

An excitation in the electromagnetic field is called an electromagnetic wave. The smallest possible part of the electromagnetic wave is called a photon. But if the photon is always accompanied by an ...
10
votes
5answers
334 views

What does a photon emitted by an atom “look” like?

Consider the emission of a photon when an atom decays from an excited state to its ground state. In most cases, this emitted photon is depicted as a small wave-packet being expelled by the atom in a ...
0
votes
1answer
32 views

Tesla coil tuning to space model

How do I model space so I can tune my tesla coil to give the most RF output at a required resonant frequency? The coil runs at 1 MHz that in aerial terms is a very short aerial so I am effectively ...
2
votes
2answers
99 views

Why isn't the electromagnetic field considered as the medium for electromagnetic waves by scientists in general?

According to a google search, the definition of a medium in physics is the substance that carries a wave. The definition of a substance in physics is matter with specific composition and properties. ...
0
votes
3answers
65 views

How to reduce edge diffraction?

I have a simple setup with a diode laser and an object placed in front of it. I want to observe the edge's shadow clearly. However, I get this very annoying effect of diffraction and interference ...
-2
votes
1answer
49 views

A question about horizontal doppler effect on galaxy hydrogen radiation observation

The figure shows the positions of the solar and neutral hydrogen regions A to D rotating in a circular orbit relative to the center of the galaxy. The sun and A to D assume a Kepler rotation. ...
0
votes
0answers
23 views

Using dipole moment when we have two positive charge

I'm looking at a problem with radiation in which two point particles (each having the same electric charge +e) travel in the xy-plane around the circumference of a circle (having radius R). At some ...