Electromagnetic Definition and 1000 Threads

Homework Statement Given an electromagnetic tensor ##F^{\mu\nu}##, showing that: $$\det{F^{\mu}}_\nu=-(\vec{B}\cdot\vec{E})^2$$ Homework Equations The Attempt at a Solution I had only the (stupid) idea of writing explictly the matrix associated with the electromagnetic tensor and calculating...

Hi, I have some confusion about the jump conditions for an electric field across an interface between two materials with different properties. In general, we have the two jump conditions across an interface: n.(ɛE)+ - n.(ɛE)- = σ...

I learned that the Poynting vector was the electromagnetic density of momentum but recently, while reading the Electromagnetic_stress–energy_tensor article at Wikipedia, I thought about the implications of the momentum conservation equation and arrived to an inconsistency, this equation is...

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...

Recently, I tried to convert an energy density ##\frac{gram}{cm^3}## into ##(\frac{Volt}{cm})^2##. I faced some problems originating from the introduction of the superfluous unit ##Ampere## and its descendants in the system of units. On one hand, there are the transparent Gaussian units, in...

Homework Statement Look at the following diagram: - copy the diagram and then label the poles for the induced magnetic field and the direction of the induced current - explain what would happen to the magnetic field and the current if the direction of motion of the magnet reversed - explain...

Homework Statement suppose a coil is placed in a changing magnetic field and the circuit is not closed will the current induce in the coil Homework EquationsThe Attempt at a Solution What I thought was that the current flows only in a closed circuit because it needs a potential difference...

Good day All! I have an issue solving this question According to my basic understanding, the displacement current goes from the positive plate to the negative plate, so whether the capacitor is charging or discharging the magnetic field direction should remain the same, but here is the the...

Homework Statement [/B] (a) At each corner of a square is a particle with charge q. Fixed at the center of the square is a point charge of opposite sign, of magnitude Q. What value must Q have to make the total force on each of the four particles zero? (b) With Q taking on the value you just...

Homework Statement In a reference frame ##S## there is a particle with mass ##m## and charge ##q## which is moving with velocity ##\vec{u}## in an electric field ##\vec{E}## and in a magnetic field ##\vec{B}##. Knowing the relativisitc laws of motion for a particle in an EM field, find the...

Problem: Look at the following diagram: · Copy the diagram and then label the poles for the induced magnetic field and the direction of the induced current · Explain what would happen to the magnetic field and the current if the direction of motion of the magnet is reversed ·...

Hello, I am reading a book on the history of the universe. The book says that we can still detect the electromagnetic waves generated at the big bang in the form of white noise. I am not sure how it works, because the waves transmitted by AM or FM radio antennas die down after propagating some...

Homework Statement Copy the following diagram and draw field lines for both magnetic fields. Then, use them to determine the direction of the force acting on the conductor. HINT: Check your answer, using the right - hand rule for the motor principle. Their diagram: 2. Relevant equation n/a...

Homework Statement A copper ring is suspended by a long, light rod pivoted at X so that it may swing as pendulum, as shown in the diagram below. An electromagnet is mounted so that the ring passes over it as it swings. The ring is set into oscillation with switch K open. What happens to the...

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 .

Homework Statement Homework EquationsThe Attempt at a Solution ## \frac { - d \phi }{dt} = V ## V denotes emf. The current is in ## \hat \phi ## direction. Magnetic force is along ## ~\hat s ## direction. Where ## ~\hat s ## is the radially outward direction in cylindrical...

Does the eye's retina, rods and cones detect the E or B or both components of a lightwave? I've not been able to find much Googling. Thanks Hank

Homework Statement Attached: Homework Equations Euler-Lagrange equations to find the EoM The Attempt at a Solution [/B] Solution attached: I follow, up to where the sum over ##\mu## reduces to sum over ##\mu=i## only, why are there no ##\mu=0## terms? I don't understand at all. Many...

For the proof I've read that verifies transverse electromagnetic waves are consistent with Gauss' Law, there seems to be the suggestion that the magnetic and electric field at a given small length c(dt), along which the waves travel, propagate infinitely backwards and forwards in their...

I have a question connected with the problem: https://www.physicsforums.com/threads/continuity-equation-in-an-electromagnetic-field.673312/ Why don’t we assume H=H*? Isn’t hamiltonian in magnetic field a self-adjoint operator? Why? Why do we use (+iħ∇-e/c A)2 instead of (-iħ∇-e/c A)2 two times?

Suppose a gravitational wave propagating through space encounters a strong magnetic field (for example the wave might pass through a magnetar with a B field strength of 10^{11} Tesla). Would there be any observable perturbation in the magnetic field itself? In other words would the gravitational...

Gravity bends light because all charged particles have mass and all electric field starts and ends on some charge particle. Is that a viable explanation for this phenomenon?

As I understand it, light is an electromagnetic wave consisting of an oscillating electric and magnetic fields perpendicular to each other. Are there experiments that will demonstrate (a) there is an electric field present? Stark effect? (b) a magnetic field, (c) that they are perpendicular to...

I’ve come to this forum because for some reason in my later part of my life I’ve become fascinated with magnetic forces... a dream has driven me to “ let’s get some magnets spinning “ attitude. I am looking for answers and guidance regarding magnetic motors and generator systems.

Homework Statement In a certain region of space, there is a uniform electric field, E = 4.28 x 104 V/m directed due east, and a uniform magnetic field B = 0.071 T, also directed due east. What is the magnitude of the electromagnetic force on an electron moving due south with a velocity of 3.09...

The Unruh temperature is given by $$T=\frac{\hbar\ a}{2\pi c k_B}.$$ As I understand it one can think of pairs of electrons and positrons popping out of the vacuum and then annihilating. Imagine that we apply an electric field ##\vec{E}## to a region of space. Each electron and positron would be...

I heard about electromagnetic pulse, that it can cause damage to electronic devices if one intentionally shots out such a burst. But I wonder, wouldn't that person him/herself be affected by the pulse? I mean, the pulse would work like a lighting. So that person could even die by his/her own...

Hi, we know that the particles have intrinsic properties for them electric field and magnetic moment, but for what I mean particles, I mean quarks, the fundamental blocks of (protons, neutrons and mesons) with everything that nobody explained as electric and The magnetic field of a particle and...

when it is asked that why radio waves do not interact with the magnetic field of electric wires or magnets, people say that radio waves are not "matter" and they do not have "charge". i really can not understand this for ex think about 2 magnets. The magnet A has a magnetic field and when we put...

Greeting I know the field of electromagnetism is not yet fully clarified but I wonder if there is an idea,theory Why does electromagnetic induction occur only when the conductor cuts the magnetic field lines.

Let's assume that a and b charges are moving. now in our lab frame there will be a electric+magnetic force whereas in a rest frame of either of the charges, there will be only an electric force. So, two inertial observers will measure different forces?

For a Dipole and a Torad (or a Solenoid) I need to find the scalar Potential,phi, Charge Density,rho, and then 4-Electromagnetic Current,J(rho*c,j) where A and J are 4-vectors and a and j are 3-vectors. -grad^2(phi) + 1/c^2*d/dt(phi) = rho/epsillon0 where grad(A(phi/c,a)) = -1/c^2*d/dt(phi)...

Homework Statement This is problem (7.1) from John A. Peacock "Cosmological Physics". Show that the first-order perturbation term for quantum mechanics with an electromagnetic field, ##(e/m) \mathbf{A \cdot p}## is proportional to the electric dipole moment. What is the interpretation of the...

What is the effect of electromagnetic fields on the Earth's magnetic field? Electric energy in the transmission and use of the process, will produce electromagnetic field, the electromagnetic field will have an impact on the Earth's magnetic field? I think it is possible to cause the...

I have encountered a problem that how electric and magnetic fields at perpendicular to each other are produce in electromagnetic radiations?

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...

According to classical electromagnetic theory,for acceleration a particle must not only change its direction but it should also increase its speed. But Maxwell said that a particle accelerates then it radiates energy.(this is with reference to Rutherford model). But actually the particle is not...

Homework Statement An electric field E exerts (in Gaussian cgs units) a pressure E2/8π orthogonal to itself and a tension of this same magnitude along itself. Similarly, a magnetic field B exerts a pressure B2/8π orthogonal to itself and a tension of this same magnitude along itself. Verify...

In classical physics, EM waves propagate this is one of the main features of all waves in general. Usually for mechanical waves the elements (like molecules) that vibrate do some little motion. For example a string can move up and down, but the waves travel further through propagation. The...

If we move towards a source of EM waves, in our reference frame the frequency appears (and it is) higher than what a stationary observer will see due to Doppler effect. The field transformations show that these two observers will se static fields differently so I would also expect that the peak...

If my professor tasked me with finding out where to find the materials for setting up an electromagnetic ring expansion test, where is a good place to start? Generally, what is a good procedure to follow when setting up an experiment? I am not very experienced but I would like to learn. The...

Hi everyone! I've been reading about these topics (Feynman lectures and more on the internet and some books) but I still have a doubt, maybe because I haven't understood the whole of it. This is my doubt: Think of an imaginary situation in which we have an accelerating charge. The...

I'm trying to understand if it does exist something (material, construction) that shiled you against alll kind of electromagnetic radiations. Something that shields you from the lowest frequency radio waves up to the highest frequency gamma rays. I've read about faraday cage but it does not...

As far as I know, we can describe the universe as if every bodies uses to follow a straight path in a curved space-time. What kind of role does the electromagnetic field play in all of this? Can we associate a "space-like" field curved by the charge of the particle with it? Does the...

I want to study Electromagnetic theory from Zero.Although i have basic knowledge of electrostatics and magnets but i do not feel confident about EM theory.I am undergraduate with Instrumentation and Control Engineering.I am preparing for National level exam in which question related to Emt...

I have these two very large (ferrous core) coils, They are basically identical, each 200mm long and have a diameter of 100mm. The core is medium grade steel One coil is receiving an input of 8V(peak-to-peak) @ 4 MHz from the function generator. The second coil is placed 1m away, and is...

There is magnetic field in B = B ##\hat z## in a region from x=0 to x=l. There is a metal rectangular wire loop with length l and width w in x- y plane with coordinates of four corners as (0,0),(0,w),(l,0),(l,w). This loop is moved with velocity v=v##\hat x##. Now according to Faraday's law...

Homework Statement These is a problem from my textbook. You have an infinite solenoid with n turns per unit longitude, radius "a" and a stationary current I. In the axis there exits a uniform line charge with lineal density λ. Compute total electromagnetic momentum (lineal and angular)...

Hello friends, Anyone ever thought of, or tried, or has come across an automobile with an EM clutch, probably electronically controlled? We have a CVT driven 2 wheeler with a centrifugal clutch, but we need to disconnect power at will (electronically), so an EM clutch was suggested. Anyone...

If I wrap a coil around a bar magnet and shoot current through the coil so that the magnetic field of the electromagnet is at the same polarity of the bar magnet will I have amplified the magnetic field of the bar magnet maintaining the same magnetic shape but bigger/stronger?