Electromagnetic wave Definition and 197 Threads

Hi, unfortunately, I can't get any further with the following task, or rather I don't know how to start: I'm also a bit confused, the task says that you have to calculate the electric field in the metal. Since it is a metal, i.e. a conductor, there is no electric field in the conductor, is it...

I want to derive the electric and magnetic field at a point around an infinitely long wire which carries a sinusoidal alternating current. And I want the answer includes the phase delay according to the limited speed of propagation of the wave. Surely the answer must satisfy the Maxwell's...

The methods of measuring the speed of light are based on the transit time of light to and from a certain path. In this way, apparently there is no way to measure the forward speed and the return speed separately and if these speeds are the same. Light is an electromagnetic wave located in the...

Since I'm computer engineer and don't have much experiences with electromagnetism, I'd like to know if it is possible to make an electromagnetic signal (250khz - 500khz) and send it to a point (with an error of maximum 1cm) in a room. If yes which devices do I need to setup my experiment?

Hi, I completely failed this homework. I mean I think I know what happen, but I don't know how to show it mathematically. The energy lost by the wave is used to oscillate the electrons inside the conductor. Thus, the electrons acts like some damped driven oscillators. I guess I have to find...

The energy of an electromagnetic wave does not depend on the frequency of the wave, only on the amplitude. Then why is light with higher frequency more energetic than light with lower frequency?

a) ##\rho = \frac{I}{c} = \frac{F}{A}## for a perfect absorber ##F = ma## where ##a = \frac{c}{t}## ##\frac{I}{c} = \frac{mc}{tA}## ##I = \frac{I^2 tA}{mc^2} = \frac{P}{A}## ##P = \frac{I^2 tA^2}{mc^2} = \frac{W}{t}## ##W = \frac{I^2 t^2A^2}{mc^2}## I am unsure what A is. I think it should be...

If the question had mentioned ##\overrightarrow{E}## instead of ##E_\bot##, then we could have used ##\overrightarrow{B}=\dfrac{1}{v}\widehat{k}\times \overrightarrow{E}## to get the direction of the magnetic field. But the question had only mentioned ##E_\bot##. To my understanding, knowing...

Hi, Since I'm dealing with a rhombus, the angle at the bottom(A) and top(A) are the same. Thus, I only have to find the angle at the bottom since the incoming beam is already perpendicular to the side of the rhombus. Since the incoming beam is perpendicular to the side ##\theta_I = \theta_T =...

Hi, I saw that the group velocity for an electromagnetic wave can be calculate with the following formula ##v_g = v_p + k \frac{d v_p}{dk}## Thus, since ##v_p = \frac{c}{n} = \frac{\omega}{k}## Is it correct to say that ##v_g = \frac{c}{n} + k(- \frac{\omega}{k^2})## where ##k =...

I saw that we can talk about the light as particles (photons ) or as an electromagnetic wave , the question is that do we represent other electromagnetic waves (like microwaves or radio waves ) as particles (like we do with light ) ?

I was reading Six easy pieces from Feynman and I got stuck what is electromagnetism 2 years ago. Recently I came across a video and I think I have figured it out. The paragraph says like this: “ If we were to charge a body, say a comb, electrically, and then place a charged piece of paper at...

Hi, If I build a machine that its sole purpose is to radiate xx Hz of electromagnetic wave, how do I calculate the intensity of the waves? Let's say I put it in the room of 30 sq meters. Thank you.

how we get "e^(ikr)"...? Plz ans me... Thanks

Calculate the wavelength for an ##E_x## polarized wave traveling through an anisotropic material with ##\overline{\overline{\epsilon}}=\epsilon_0diag({0.5, 2, 1})\text{ and }\overline{\overline{\mu}}=2\mu_0## in: a. the y direction b. the z direction Leave answers in terms of the free space...

A common equation for an electromagnetic wave is Ey = Eocos(kx - wt + phi). According to this equation, wouldn’t the intensity of the electric field extend indefinitely in the y-direction? How does this make sense?

light is electromagnetic wave ,so does it also have magnetic and electric field,like all others waves(micro,gama,xray,radio waves etc..)? i never heard that some one talk about light in sense of magnetic and electric field.. if it has ,why than compass don't response to light?

no need of equations

Homework Statement: In the attached image. Homework Equations: formulas of fringe width and phase differences I think. It has been a long time since I have dealt with these kinds of interference/fringewidth problem, I can't figure out a way to start solving this problem. I was thinking about...

Hello all PF members! I was wondering about the power dissipated by resistor at high frequency which is: ##P=Re\left \{ U\cdot I^{*} \right \}=Re\left \{ \frac{\left |V^{+} \right |^{^{2}}}{2\left |Z_{c} \right |}\cdot (1-\left |\Gamma \right |^{2} )\right \}##, (1) where: ##Z_{c}## -...

Hi there, I'm failing in simulating the fresnel equations in 2D with Comsol. As you can see in the model added to this post, the reflectance and transmission in the global plots both for TE-waves ("Port, senkrecht polarisiert", Plot "Reflektion und Transimission, senkrecht") and TM-waves...

When there is electric charge, then there is an electric field in space aorund it. Or when the electric charge is moving (without acceleration), then it is produced magnetic field in a space around it. Both of these fields permeated to infinity according to Maxwell theory. But how fast...

Homework Statement An isotropic point source radiates electromagnetic energy, and its output is measured by a thin disc-like detector of radius R. Calculate the power measured by the detector at distance h from the source, assuming that the plane of the disc is orthogonal to the line of sight...

As I understand space time fabric is exclusively the Gravitational field according to Einstein.So every field wave or interaction is contained in the Gravitational Field.This fabric of spacetime(gravitational field) is having properties of inertia and elasticity that is why gravitational waves...

There are some things that confuse me about electromagnetic waves, and I haven't found good answers anywhere. Consider the following equation: E=E0 e i(wt-kx) (here E and E0 are vectors, I couldn't find the right symbols). The things that confuse me are the following: 1° We say that the power...

Hello PF, first of all I don't know where to put this post as it's not exactly a homework question but a clarification question for a project. I'm going through the derivation of the effective permeability of two stacked medias, given the polarization of an incoming EM wave but I'm stuck at the...

Hi to everybody ! I was thinking about something which confuses me about wave emission. The question is simply the following: Does an electron emit light when it accelerate? or just during its deceleration? or maybe when acceleration and deceleration alternates in some order? I'm not really...

Do electromagnetic waves have potential and kinetic energy like springs, strings, etc. If so how are they calculated, inter-related? What is the total energy? Are the energies fluctuating over time? I am a physics hobbyist so generally the first answers should come with the least mathematics...

As far as I understand, two electric fields can interact with each other (for instance, two charges being brought close to each other will either repel or attract). A photon is an EM wave and when it comes in contact with a charged particle, say, an electron, the electric field of the wave...

I explain it better. If we bring an electron from higher to lower energy level, the energy gap will be emitted as electromagnetic wave, because of the conservation of energy. When the same situation applies for a physical body, for example letting if falling down from some height, what does it...

Homework Statement An EM wave from air enters a medium. The electric fields are --> ^ E1 = E01 cos(2πv(z/c-t) x --> ^ E2 =E02cos(k(2z-ct)x in a medium ,where the wave number k and frequency v refer to their value in air.the medium...

I know that Maxwell discovered that a disturbance in the electromagnetic field propagates at the speed of light - which Occam's razor would say that light being such a wave would explain it - but not definitively that that is true (e.g., gravity waves, or at least at that time in history, some...

Homework Statement : [/B]This is a general conceptual doubt, not a numerical based doubt. We were taught that when an electron(or any charged particle) moving with uniform velocity enters a magnetic field(perpendicular to its direction of motion), then a force acts on the electron which makes it...

when a em waves strikes a dielectric the atoms vibrate in response to the electric field and if the frequency matches the resonant frequency the Lorentz oscillator the electric field is absorbed how a field can be absorbed we know the em field contain energy how is the em field destroyed is some...

When why sey that light is electromagnetic wave i understand this. But what i do not understand is where photons come into picture ? can somebody explain me the relationship between those two . My knowledge in this respect is not great so I would ask that the answers be adjusted .

What types of light are able to pass through the human body without causing damage to tissue or individual cells? Are there any truly safe alternatives to x-rays that could allow doctors to see internal body parts but not cause damage from extended exposure?

I have asked a form of this question previously: https://www.physicsforums.com/threads/electromagnetic-waves-and-polarity.857347/ ...but have come back to it in slight confusion. Say I have this antenna and the voltage source is increasing with a constant acceleration of its voltage. It...

The speed of light (in the vacuum) is a function of the permeability and permittivity of the vacuum. In other mediums the phase velocity will be different. It is assumed (by me) that the speed of a gravitational wave does not change depending on the medium i.e. a gravitational wave would not...

I know this question might be too simplified but, What is the primary causes generation of light (electromagnetic waves) by electron? Is it vibration motion of electron or the motion of electron around the nucleus?

What composes the E Field of the Electromagnetic Wave where "disturbances" for propagation occurs? If electromagnetic waves cause disturbances in the Electric Field… what “is” in this E Field which photons Interact with? I ask because in Vacuum, there are no electrons to excite. So what is...

Homework Statement .[/B] On the course, I was asked a question: What is less absorbing electromagnetic wave: metal or glass? Explain why. The Attempt at a Solution Now, I'm not sure if i did it correctly. I answered that glass is less absorbing electromagnetic wave due to it's structure and...

Homework Statement Homework EquationsThe Attempt at a Solution So I was given the electromagnetic E field equation in phasor form and I converted it to sinusoidal form. Is it correct ? Also will it be a reflected wave since we have (wt+Bz) and not (wt-Bz) ? Also will it be circularly...

Hi. I'm a bit puzzled that the classical formula for the intensity of a monochromatic, linear EM wave $$I=\frac{1}{2}\cdot c\cdot \varepsilon_0\cdot E_0 ^2$$ seems to be independent of frequency whereas I find for the energy of a mechanical wave (e.g. on a string with total mass ##M##)...

Hi, i came across this video on BBC yesterday: <link to video deleted> Now I wonder how this stuff works in detail? Is it the carrier wave or the multiplexer signal of the phone? best regards

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Hi there When a charge is accelerated it produces electromagnetic radiation. I was wondering if anyone knew the equation relating the frequency of emitted radiation to the size of the charge and the value of the acceleration. My understanding is that it relates to Maxwell's equations, but I was...

For any given number(length), say L, is always there an electromagnetic wave with the wavelength L ? As I know, the source of electromagnetic wave is the energy emission of electrons changing it's quantum state in an atom. But there are at most about 120 atoms there, and the quantum numbers...

Homework Statement A harmonic EM-wave is propagating in glass in the +x-direction. The refractive index of the glass ##n = 1.4##. The wave number of the wave ##k = 30 \ rad/m##. The magnetic portion of the wave is parallel to the y-axis and its amplitude ##H_0 = 0.10A/m##. At ##t=0## and ##x =...

Homework Statement ⃑E = Eo cos(4.0y−1.2 × 109 t) ̂ (N/C) where y is in meters and t is in seconds. The intensity of the wave is 200 mW/cm2 . (a) In what direction is the wave propagating? (b) What are the wavelength and frequency of the wave? (c) What is the peak value of the electric field...

Hi, light as an EM wave attributes wave-particle duality. In general, are the other bandwidths of EMW (UV & IR for example) qualifies the same duality? How? Why and why not?