Fields Definition and 1000 Threads

I am having a very difficult time picturing space-time and fields and all... Anyone here have a sort of flow chart or procedural chart that I could use to try to better wrap my head around what this place is? Sort of starting with universe and then going into spacetime and from spacetime to...

I read in a book that Electromagnetic fields propagate at speed of light and carry energy and momentum. Let's take electric field for example. Electric field is none other than a force per unit coulomb.So 1.How could a force(here field) move as force has no property of moving as force causes...

Hi there! It has happened to me these days when I went to a conference that I realized maybe my PhD topic is something I would like to work in after it (IF I continue in the academic path). My current research is based on applying QFT in condensed matter physics, particularly related to the...

The field strength of gravitational, electric and magnetic fields vary as the inverse square of the distance from the source. Is this because all of the above fields are generated by fermions and they behave identically regardless of the nature of the fields ? Do the above fermions have rest...

Dummit and Foote in their book Abstract Algebra give the following definition of an algebraically closed field ... ...From the remarks following the definition it appears that the definition only applies to K[x] ... Does it also apply to K[x_1, x_2], K[x_1, x_2, x_3], \ ... \ ... \ , K[x_1...

Dummit and Foote in their book Abstract Algebra give the following definition of an algebraically closed field ... ... From the remarks following the definition it appears that the definition only applies to ##K[x]## ... Does it also apply to ##K[x_1, x_2], K[x_1, x_2, x_3], \ ... \ ... \ ...

Hi, I've been trying to figure several simple things about electric and magnetic fields, their relationship with current. If you could please help me understanding this, it would be really helpful. From what I've read these were presented as natural laws: 1. Changing magnetic field induces...

I was researching the relationship between magnetic dipoles and chemical bonding and I came across a very interesting paper. I'm hoping some of you can shed some light on how magnetic fields are making dissociation of a molecule possible and how to measure it...

I thought I'd post this here since it's not exactly a homework question or discussion regarding a specific operation in a field/subject. Out of the following, which fields gravitate more towards applied physics/engineering (but not necessarily such a discipline)? Or maybe if that's confusing...

Hey all, I'm having some issues with electromagnetism here. Let's say we have a particle with magnetic moment ##\vec{\mu} = \mu_0 \hat{x}## and magnetic field ##\vec{B(x)} = B_0 \frac{x}{a} \hat{x}## where ##\mu_0,B_0,a## are constants. If we assume that the magnetic field ##B_0## is far, far...

By electitc field, i do not mean the magnetic field produced by a current carrying wire, but rather between charged particles. If a compass is placed between the electric field, will the compass needle delfect or will it just continue pointing in the initial direction?

I know that magnetic fields create moving charges (an electric current) normal to the plane of the magnetic force lines. I also have heard that magnetic and electric fields create each other in a perpendicular direction to the other (badly worded). Electric currents are moving charges (usually...

<<Moderator note: Split from thread Photon the smallest particle>> @Orodruin - Let me ask a question. This is an aspect of QFT that has always puzzled me. Suppose we have an RF cavity or a laser cavity with a standing E-M wave. I understand that we can view the field in the cavity as a...

Homework Statement In the figure two large, thin metal plates are parallel and close to each other. On their inner faces, the plates have excess surface charge densities of opposite signs and magnitude 7.76 × 10-22 C/m2. What is the magnitude of the electric field at points (a) to the left of...

I've read a few other threads on the site, and many say that it's hard to get a job that has to do with Physics, at least with only an undergraduate degree. Is that true? I'd like to get onto physics because I'm curious to know more about the science, but I wouldn't like to end up working as an...

When we encounter particle-collision problems that call for invoking the conservation of four-momentum, are we tacitly assuming a field-free idealization (or at least negligible potential energy)? For example, say particles 1 and 2 collide elastically. Then the conservation of four-momentum...

I'm interested in Killing vector fields and want to ask whether anybody can name me a good textbook or online-source about them, preferably with a general treatment with local coordinates as examples and not at the center of consideration.

Homework Statement Given two vector fields ##W_ρ## and ##U^ρ## on the sphere (with ρ = θ, φ), calculate ##D_v W_ρ## and ##D_v U^ρ##. As a small check, show that ##(D_v W_ρ)U^ρ + W_ρ(D_v U^ρ) = ∂_v(W_ρU^ρ)## Homework Equations ##D_vW_ρ = ∂_vW_ρ - \Gamma_{vρ}^σ W_σ## ##D_vU^ρ = ∂_vU^ρ +...

Homework Statement So I was given some questions as practice, and I can't seem to do them. Here is a link to the questions: http://i.imgur.com/ZmkqCAV.jpg (the answers are in square brackets) Ive only been able to calculate Q3 and Q2 so far. I would really especially like help with Q1. I've...

So in conductors, the electrons will distribute themselves to the surface via repulsion forces. But why do we say that the electric field inside is zero? If I put a positive charge inside, clearly it will move in some direction from the electric field of generated from the electrons. Also, are...

Hi All, It is said that iron has a high "permeability" for the magnetic field, it let's the magnetic field pass through it more easily. But it is also said that iron screens the magnetic field? Don't these two contradict themselves? Thanks, Ionel

In my post graduate course, several years now, our professor in field theory have mentioned that in field theory the fields of mass-energy seem to be space and time themselves, like electric and magnetic fields in ElectroMagnetism. Specificaly he said that "the problem is that in...

If I have a some a wire and I took part of it and created a circle. If I want to calculate the strength of the magnetic field at the center of it. I should just use the magnetic field equation for the circular loop, shouldn't I? ## B = \frac{U_o N I}{2R} ## and I shouldn't care about the...

I have made a similar post to this in the past, but it was a very long time ago, and my perspective on the issue has changed since then, so I felt this post could be helpful. I have just finished my second year of college; during those two years I've nearly completed my Associate's degree in...

1. If e.m.f is NOT a force, but actually energy – and e.m.f is measured in Voltage – then why is p.d. (V) NOT used up? Since we know energy *does* get used up by the component. I know the electrons are just the medium – energy carriers – but Voltage doesn’t mean number of electrons; it means...

Homework Statement Two identical conducting balls, b1 and b2, each with a mass of 25.0g both are hanging at 50.0cm at an angle of 45Degrees from the vertical each. Homework Equations Fg = mg Fe = kq/r^2 Ft = ? The Attempt at a Solution I made a free body diagram and am confused on what to do...

Hi all! ObiWanKenoobi here... it's my first post. My question is on a few levels based on my rudimentary understanding of most things. 1. If you have a ball of molten metal which is tightly compressed to behave almost like a solid... HOW is a magnetic field generated if the ball rotates on an...

So from Faraday's law, a change in the magnetic flux will induce an emf on a loop of wire. { \phi }_{ B }\quad =\quad BA\\ { \varepsilon }_{ ind }\quad =\quad \frac { d{ \phi }_{ B } }{ dt } (in this case a perpendicular field) From these equations, it looks like the only way to induce a...

Homework Statement Vector field is given by: [PLAIN]http://tutorial.math.lamar.edu/Classes/CalcIII/LineIntegralsVectorFields_files/eq0001M.gif[PLAIN]http://tutorial.math.lamar.edu/Classes/CalcIII/LineIntegralsVectorFields_files/empty.gif I'm just reviewing line integrals of vector fields and...

How come the magnetic field outside a solenoid is practically zero? I've read reasons along the lines of: -The magnetic field cancels out on the outside. Of course the net force cancels out, but what if you have an object placed on just one spot? The force on that object clearly is not 0...

Can someone please help me out with this practice test and provide explanations?

When deriving the magnetic field strength due to a circular loop at some distance away from it's center (using Biot-Savart's law), why is the angle between ds and r 90 degrees? This is a youtube video with the derivation, see 5:55

Homework Statement What is the electric field strength at the position of the proton in the figure?(Figure 1) Assume that B = 0.10 T and F = 3.4×10−13N . Figure 1: https://session.masteringphysics.com/problemAsset/1385081/6/35.P29.jpg Homework Equations Honestly I don't know. Since we have a...

Homework Statement Using the tensor transformation law applied to ##F_{\mu\nu}##, show how the electric and magnetic field ##3##-vectors ##\textbf{E}## and ##\textbf{B}## transform under (a) a rotation about the ##y##-axis, (b) a boost along the ##z##-axis. Homework Equations The Attempt at...

Homework Statement The figure shows a cross section across a diameter of a long cylindrical conductor of radius a = 2.92 cm carrying uniform current 151 A. What is the magnitude of the current's magnetic field at the center of the conductor? Homework Equations Biot-Savart's Law The Attempt...

Homework Statement The figure shows two very long straight wires (in cross section) that each carry a current of 3.19 A directly out of the page. Distance d1 = 6.00 m and distance d2 = 4.00 m. What is the magnitude of the net magnetic field at point P, which lies on a perpendicular bisector to...

Homework Statement I am having some trouble with gravitational force and fields and would like some confirmation if I am on the right track and approaching the questions correctly. I have attached a couple of problems that I have worked through below. Homework EquationsThe Attempt at a...

[moderator note: Thread title changed to make it descriptivie of the problem] Homework Statement A particle having mass m and charge q is released at the origin in a region in which magnetic field and electric field are given by B= -B' j and E= E' k where j and k are unit vectors along y-axis...

Homework Statement If linear charge density is equal to 1micro coulomb per meter, then what is the electric field intensity at O? Homework EquationsThe Attempt at a Solution The electric fields due to the two straight lines should cancel out.. But how to progress further? Please let me know...

Homework Statement Two short dipoles each of dipole moment p are placed art origin. The dipole moment of one dipole is along x-axis while that of other is along y axis. Then what will be the electric field at a point (a, 0)?Homework Equations The direction of electric field due to axial dipole...

Homework Statement Two charged metallic spheres of same size repel each other by a force F. They are now touched with each other and are then separated to same initial distance. Now the force of repulsion is F'.Homework Equations On touching the spheres will reduce their charges... So the new...

Two identical small bodies each of mass m and charge q are suspended from two strings each of length l from a fixed point. This whole system is taken into an orbiting artificial then the tension in strings is... The answer has to be kq2/4l but how? Can someone please explain? Plus its not a...

My syllabus has point *' 'describe and compare the forces on mass, charge and current in gravitational, electric and magnetic fields, as appropriate" what does this mean ?

The solution to the One-Dimensional Time-Independent Schrödinger equation for an electric potential field of constant value is an exponential function, and its energy eigenvalue can have any value, it is not quantised. Are there any other potential field functions whereby the energy of the...

What statement about magnetic fields interacting with a moving charge is correct? A) Magnetic fields can’t change the direction of motion of a moving charge. B) Magnetic fields can do work on a moving charge. C) Magnetic fields can accelerate a moving charge. D) The force on a moving charge in a...

What statement about magnetic fields interacting with a moving charge is correct? A) Magnetic fields can’t change the direction of motion of a moving charge. B) Magnetic fields can do work on a moving charge. C) Magnetic fields can accelerate a moving charge. D) The force on a moving charge in a...

The following is taken from pages 99 and 100 of Warren Siegel's textbook 'Fields'.We begin by reviewing some general properties of symmetries, including as an example the symmetry group of nonrelativistic physics. Symmetries are the result of a redundant, but useful, description of a theory...

Consider a theory with two multiplets of real scalar fields ##\phi_i## and ##\epsilon_i##, where ##i### runs from 1 to N. The Lagrangian is given by: $$\mathcal L = \frac{1}{2} (\partial_{\mu} \phi_i) (\partial^{\mu} \phi_i) + \frac{1}{2} (\partial_{\mu} \epsilon_i) (\partial^{\mu} \epsilon_i)...

Let f(x)=x4-2x2+9 Find the splitting field and Galois group for f(x) over ℚ Here is what I have written out so far. If I have found the splitting field E correctly, have I proceeded with the Gal(E/F) group correctly? Also, how would I go about finding the roots of this equation by hand...

Given this diagram: Two wires, having parallel and opposing current flows( Where ## I_1 = I_2 ##), creating opposing and equal magnetic fields near a ferromagnetic object(##F##), since the magnetic field of each wire is not uniform, I'm not really certain how to figure out the magnetization of...