Electromagnetic Definition and 1000 Threads

May I know that are there any different between the electromagnetic flux and magnetic flux? Are there any electromagnetic flux in a permanent magnet machine? What kind of flux will go through the permanent magnet machine's stator cores with copper wires on it? I am really sorry to ask so many...

Homework Statement Use the integral form and symmetry arguments to compute the electric field produced by the following charge densities: (i) Point charge q, placed at the origin, in 3 dimensions; (ii) Point charge q, placed at the origin, in 2 dimensions; (iii) Point charge q, placed at the...

In order to determine the temperature that an electromagnet reached after a 3 minute period the electromagnet was placed in a constant volume of water. After 3 minutes the change in temperature of the water was measured and from this using the equation Q=mcΔT the energy in joules transferred was...

hello world. it is know that electrostatic (coulomb's law) and magnetostatic (biot-savart law) fields lose their strength like 1/r^2. why do they say that electromagnetic field falls like 1/r ? is that true ? if yes how, can you explain please ? after all energy radiated from a point source must...

I hope this is the right forum for a first year undergraduate problem! The problem I've been working on is here: http://i.imgur.com/IhTtL.png I think that I have the correct answers, but I'm not sure. I think that the energy densities of the E and B field components will be (0.5)(ε0)(E^2)...

When a conducting wire is subjected to a changing magnetic field, what causes the electrons in this wire to move? Conversely, why does the movement of current in the wire (with a non-'moving' magnetic field) cause the wire to move? I understand these phenomena macroscopically (and that they...

Is it possible for EM radiation to exist outside the EM spectrum? I'm aware of the different frequencies at which energy can be radiated eg. radio, infrared, and gamma. But is it possible for objects to absorb or release energy at subradio or supergamma frequencies? Or is there a physical law...

Hi i was wondering what's is the difference between electromagnetic waves and fields or is a field just a number of electromagnetic waves. also i was wondering is it possbile to have an electromagnetic wave where there is only a magnetic field and no electric field and vice versa Thanks

Homework Statement A solid sphere of radius a rotates with angular velocity ω\hat{z} relative to an inertial frame K in which the sphere's center is at rest. In a frame K' located at the surface of the sphere, there is no electric field, and the magnetic field is a dipole field with M=M\hat{z}...

The covariant form of the Lorentz force can be written as m \ddot x^\mu =q F^{\mu \nu} \dot x_\nu and such a relation should prove by the quotient rule that F is indeed a tensor. But what kind of tensor is it? One can show that it transforms from an unprimed to a primed system like F'^{\mu...

I can find the metric tensor in cylindrical coordinates to be [1,-1,-1/r^2,-1] but how about the electromagnetic field tensor and thus the energy stress tensor? Is it just change the Ex,Ey,Ez to Eρ,Eθ,Ez? Is FσρFσρ still equal to 2(B^2-E^2)

1. How do we observe what goes through in a slit in the double slit experiment? If this is accomplished with EM that goes across the slit, then why does the electron not completely change its direction before it hits the wall. It still always hit the wall where you expect it to, even though the...

I apologize in advance if some of my answers don't quite make sense. I'm generally articulate, but not when it comes to physics I'm barely grasping. I did a lab and part of it was dropping a magnet through a coil, which produced a Voltage vs Time graph using LabPro. For trial 1 we had the N...

Hey guys, back again for some help if that's okay! I've derived a formula for an electromagnetic wave entering a material, as \underline{E}e^{-\frac{x}{\delta}}e^{i(\frac{x}{\delta}- \omega t)} x=direction of propagation t=time \delta=skin depth As you can see this describes the wave...

Homework Statement A flat coil of wire has an area of 0.010 m2and contains 100 turns. Initially the coil is oriented so that the normal to its surface is parallel to a downward constant magnetic field of 0.2 T. The coil is then rotated clockwise through an angle of 30oin a time of 0.10 s...

Hi I'm working on a science experiment and I need two electromagnets to push away from each other, but the two small electromagnets I've made (using two bolts wrapped in magnet wire and a D battery) just attract each other no matter which ends I put together. Am I doing something wrong? Do I...

Homework Statement An electric generator consists of n = 500 turns of wire formed into a rectangular loop with a length of 5 cm and width of 3 cm placed in a uniform magnetic field of 2.50 T. What is the maximum value of the emf produced when the loop is spun at f = 100 rpm about an axis...

Hi Much of what I am going to write in this post is based on what I have read and understood (with very, very limited knowledge of the subject) on the Internet. So, if I have been misinformed or I have misunderstood anything, please don't hesitate to correct me. I would appreciate it. As...

Homework Statement This isn't a homework problem but I am very curious. How much voltage can a magnetic, about the size of a fist, generate by passing through a solenoid with about 3 loops every centimeter with being pulled by a tension of 1000 N over a distance of 2 meters...

When a magnet is pushed into a solenoid an induced emf occurs. So if it is a closed circuit then an induced current will flow. But if it is an open circuit then an emf will still be induced but no current this time. So will any poles be formed to repel it? What do they mean by the current...

What will happen when I push a magnets into a solenoid with constant speed throughout? I understand that when the magnet leaves and enters an induced emf will occur, but in the middle no emf will occur. Why is this so? I thought that the magnetic flux linkage changes as it moves in the solenoid?

A platinum aperture from a transmission electron microscope exhibits atomic variations after prolonged exposure to electromagnetic radiation. A gold aperture on the other hand does not. Using a backscatter electron detector we can observe sturctural features of materials below the surface...

I have heard that the strong nuclear force is stronger then the electromagnetic force at short ranges, "Up to two and a half times the proton diameter". Ok, so i have an approximation of the length it dominates over the electromagnetic force, but i don't know where the force starts from; is it...

Homework Statement I attach a word document with the equations because I don't know how to write them on the post. My question reads: Show that Maxwell's equations Eq (1) is equivalent to Eq (3).Homework Equations The first term of Eq 1 reads: F sub alpha beta comma gamma. That means partial of...

Can anybody tell me the basics of EM waves...like what constitutes EM wave...what is displaced...what are electric and magnetic field components...?

Bohr model had a flaw that electrons would emit EM radiations and would spiral into the nucleus - but he just said that it wouldn't happen providing no reasons Do the modern models of atom explain - why electrons won't emit EM radiations?

Hi What was the evidence that led Maxwell to conclude that light is an electromagnetic wave? How do we measure the strength of the electric and magentic fields of a light beam ? TIA

I'm trying to use some home-made electromagnets to lift a small object. I am a college student, but this is a personal project, so while I may reference something from a textbook, its not a homework problem. I know that I can get some iron bar, coil it with wire, run some current through it...

I like to know if electromagnetic waves pass through a medium (Glass) and if this medium were in contact with two other mediums in its boundary which the first one with same optical dense (Glass) and the second with less optical dense (air). Is there any tendency or priority for wave to pass...

I have to simulate the motion of particle in an electromagnetic device which deflects particle using electric and magnetic field. Those field are arranged in such a way that the electric field is inside the magnetic one. Moreover the electrodes begin at the center of the magnetic field ad their...

Einstein stated in a paper concerning the discovery of the quantization of electromagnetic force that an object emitting electromagnetic radiation will lose its inertial mass. If this is the case, then why does the gravitational force of the sun not weaken and the sun not become less massive as...

First: Since photons carry electromagnetic force between charged particles, and the gravitational force is presumably separate (at least at typical energy levels) then is it correct that an object's mass is irrelevant in considering electronic(electromagnetic) attraction/repulsion? i.e. an...

Basically I couldn't understand Maxwell's equations during my college days mainly because I didn't understand divergence and curl intuitively. I need some good book on Electromagnetic Fields (such as Gauss Laws and so on) and also I want to learn about Maxwell's equations. I want to...

What keeps the current in an electromagnetic coil from moving between the touching conductors and instead go through the conductor? Is it the resistance being much higher between two touching sections of the coil? Is there a small amount of current "leaking" between each loop where they touch?

In 2-5, an analogy is given for electromagnetic field: two corks in water, and the effect of jiggling one cork on the other (probably the up and down motion). Now, that sounded more like water is a medium propagating the energy. But the electromagnetic waves require no medium for propagation...

Repulsion's got a nice, 'this emits that, hits this; see Newton's third Law' explanation. Attraction. I found one thing. It says this: A virtual particle with momentum p corresponds to a plane wave filling all of space, with no definite position at all. It doesn't matter which way the...

Homework Statement Let (V(x,t) , A(x,t)) be a 4-vector potential that constructs the electromagnetic field (in gaussian Units) by E(x,t) = -∇V(x,t) - (1/c)δtA(x,t) , B = ∇xA , (x,t) elements of R3xRt Consider the lagrangian L=.5mv2 - eV(x,t) + (ev/c)(dot)A(x,t) a) compute and interpret the...

I've always thought that photons and electromagnetic waves are one in the same. And I still do, but I'm trying to get a better grasp on the idea and am finding it difficult. 1) As I understand it, they are the same. But an electromagnetic wave with definite frequency is a perfect sine wave...

An electrically charged particle has an electric field centred around itself that extends far into space. That field has an energy density proportional to the electric field squared. By Einstein's E=mc^2 that energy density is equivalent to a mass density. Thus, as a charged particle...

Homework Statement The diagram below shows two pith balls, equally charged and each with a mass of 1.5 g. While one ball is suspended by a thread, the other is brought close to it and a state of equi- librium is reached. In that situation, the two balls are separated by 2.6 cm and the thread...

This was a question on an online homework for a modern physics class. I had two chances to answer it, but I was wrong both times, so I'm simply curious what the answer is. Homework Statement The Attempt at a Solution (a) Quarks attracted to one another is the strong force (b) A...

Biot-Savart's law of magnetic field " electromagnetic fields" Homework Statement A rectangular loop carrying 10 A of current is placed on z=0 plane as shown in figure . Evaluate H at a) (2,2,0) b) (4,2,0) c) (4,8,0) d) (0,0,2) Homework Equations the used...

Homework Statement A charge q is released from rest at the origin, in the presence of a uniform electric field and a uniform magnetic field \underline{E} = E_0 \hat{z} and \underline{B} = B_0 \hat{x} in frame S. In another frame S', moving with velocity along the y-axis with respect...

If two magnets, equally but oppositely charged, were placed one on top of the other, such that they repel each other, but the weight and shape would not allow the top magnet to slide off, what energy is generated by the relative weight (gravity acting on the mass) of the top plate overcoming the...

best book for "Electromagnetic Theory & Transmission Lines" We've this subject of "electromagnetic theory and transmission lines" this semester..and i wanted to know which books deal the content properly ...mastering this topic may require that one cool book (and ofcourse, regular effort)...and...

Would it just be the energy of the wave (i.e. E = hf)?

I need some help with properties of electromagnetic fields in the presence of microwaves. specifically will a electromagnets field, powered by an external power supply, function normally in a microwave chamber? Will the magnetron induce a current in the copper coil? Would the external power...

Hi all, I'm trying to understand exactly what the physical meaning of conductivity/current is in relation to waves. if we have a wave traveling through a conductor, we find that it decays exponentially, i.e. e^{-\alpha z} where \alpha=imag(k)=\omega\sqrt{\frac{\epsilon\mu}{2}}...

I understand that electromagnetic induction is determined because of a moving electric charge in a magnetic field, but why is the motion necessary? Why is it that motion causes electromagnetic induction and it isn't possible without motion?

Hi! In some texts (Sakurai - advanced qm and others) I found this expression for the lagrangian of an em field: L=F_{\mu \nu}F_{\mu \nu} but I'm a bit confused... L must be a Lorentz invariant, so I would write instead: L=F_{\mu \nu}F^{\mu \nu} \;\; Which form is the correct one? Or...