Fields Definition and 1000 Threads

Homework Statement Two positive charges +Q are affixed rigidly to the x-axis, one at x = +d and the other at x = -d. A third charge +q of mass m, which is constrained to move only along the x-axis, is displaced from the origin by a small distance s << d and then released from rest. (a) Show...

"a +4nC charge is 6/0 cm along a horizontal line toward the right of a -3nC charged object. Determine the E field at a point 4.0 cm to the left of the negative charge." From what I understand, it goes Point ___ 4cm ____ (-3nC) _____ 6cm ____ (+4nC) Using that, I got the answer to be -14.75 nC...

Homework Statement I am going through the book "Symmetries in Fundamental Physics" by Kurt Sundermeyer and in his part on deriving Yang-Mills theories from a Kaluza-Klein perspective I seem to be stuck on a small step in the derivation. Homework Equations He expands the metric in a typical...

Hi, I need your help with the next two problems: 1) If p is a prime number such that p\equiv{3}\;mod\;4, prove that \sqrt{-p} is prime in \mathbb{Z}[\sqrt[ ]{-p}] and in \mathbb{Z}[\displaystyle\frac{1+\sqrt[ ]{-p}}{2}] too. 2) 2) We have d > 1 a square-free integer. Consider the quadratic...

It's easy to find references which explain that the photon is the force carrying particle for the electromagnetic force (ie https://en.wikipedia.org/wiki/Force_carrier). Similarly there are force carrying particles for other forces, like W and Z bosons carry the weak force. This has always...

I know this question has been beaten to death, but I haven't seen a response that clearly (to me) answers the following: 1. Magnetic fields *can do work* on intrinsic dipoles, right? (e.g. two electrons can do work on one another via their intrinsic spin). 2. Magnetic materials can do work on...

if there is an uniform, infinitly extended,magnetic field that is changing with a law B(t), I can calculte the induced electric field using an arbitrary circle; then the induced circuitation on the circle is \epsilon _i=-\pi r^2 \frac{dB(t)}{dt} , and since the symmetry of the system ( infact...

Does QM contain both discrete particles and fields? If so, why aren't these two mutually exclusive? It seems like one is chunky and the other continuous.

Homework Statement 560 nm light is collimated and passes as a parallel beam in a direction perpendicular to the ##x+y+z=0## plane. It is polarized parallel to the ##(y-z)## plane. Treating it as a plane wave, what are the real E and B fields? Intensity of the beam is ##1 \ mW/cm^2##. Make...

Homework Statement This isn't necessarily a problem, but a question I have about a certain step taken in showing that the electric and magnetic fields are transverse. In Jackson, Griffiths, and my professor's written notes, each claims the following. Considering plane wave solutions of the...

Hi guys, I was tutoring some students and I was explaining them how to calculate the capacitance between two parallels planes. They made me some questions and actually I am not quite sure about my answers! I started by showing them how to calculate the electric field generated by a single...

For the Godel metric (in Cartesian coordinates), I derived the Einstein tensor Gμν as well as its inverse Gμν in a coordinate basis. I tried converting the inverse into an orthonormal basis using a technique for this that was taught to me on another thread long ago. When I tried using said...

Hi everyone. I have written similar threads about this in the past, but I thought that now would be a good time to revive this topic (as a snapshot of STEM demand, if you will). So I would like to ask the following questions: 1. Which STEM fields are actually in demand in the US as of 2015? 2...

Homework Statement Assume that I = 5.0A. What is the magnetic field at point b in the figure? Give your answer as a vector. Homework Equations Ampere's Law - B = (μ0I)/(2πr) The Attempt at a Solution I tried plugging the given numbers into Ampere's Law for point b, which gave me B =...

Problem I have a project for my university class on the Higgs fields and how it impacts the standard model, and how the Higgs particle is formed and decays into particles with the probability of decay based on the mass of the particles it will decay into. I need resources that I can cite like...

Homework Statement Reading a journal from that crazy old retired physics professor on the hill, you stumble upon a scheme to generate high frequency (HF) radio waves (λ = 10 m). It requires generating an electric field that diverges from a point and increases in strength linearly with respect...

I am a third year undergraduate physics major. Often time people ask what I want to do with physics, and I didn't really have an answer for them. I guess I always assumed I'd pursue a masters degree in some kind of engineering, but I want to be able to do something that I'm passionate about...

Hi I am doing some exam revision for an EM class and I'm trying to understand a few things about this derivation. Specifically in equation 18.23 why do we not consider the derivative of the four velocity i.e ##\partial^{\alpha}U^\beta## Then going from 18.23 to 18.25 why is...

I'm going to ask a very general question where I just would want to hear different possible methods that can be thought of in this kind of problem. I am trying to solve a very specific problem with this but I won't talk about that because I don't want someone to give me the answer but ideas for...

Homework Statement Consider the charging capacitor in problem 7.34 (A fat wire, radius a, carries a constant current I, uniformly distributed over its cross section. A narrow gap of wire, of width w, w<<a, forms a parallel-plate capacitor) a) Find the electric and magnetic fields in the gap, as...

I like getting all knowledge and also like being an all rounder. I like Maths, physics and chemistry. I think in mechanical engineering only mechanics is taught. In which branch all topics are taught? Or can one choose various fields like elec engineering, chemical engineering, computer science...

a simple idea. Maxwell’s theory of magnetic fields says there is two components ,an electrical field and a magnetic field. (put simply). I have an idea to pick up radio waves using a magnetic beam. rather than the normal dipole set-up, just wondering if you think this idea is possible to make...

Homework Statement What is the magnitude of the magnetic field inside the solenoid at t = 1 ms? Homework Equations Not sure The Attempt at a Solution Well I would make an attempt but firstly I have a question. What I want to know is the above question simply referring to the emf of the...

Examine the charge distribution shown: b) What is the net electric field acting on charge 1? Attempt at the answer: E2 = Kq2/r2^2 = (9.0 x 10^9 Nm^2/C^2)(3.0 x 10^-5 C) / 2.0m^2 E2 = 6.75 x 10^4 N/C E2 = E3 ( therefore, same procedure) eNet = Sqr.rt. 6.75 x 10^4 N/C^2 + 6.75 x 10^4 N/C^2...

Homework Statement Homework Equations n/a The Attempt at a Solution I don't understand how the book went from calculating Green's theorem on ##\int _c Pdx + Qdy + \int _{-c'} Pdx + Qdy = ## (1 in the attached picture) to getting (labeled 2) ##\int _c Pdx + Qdy = \int _{c'} Pdx + Qdy ##...

Homework Statement Need someone to confirm if I answered correctly. Thanks for your support :) A) Draw the pattern of the gravitational flux passing through a horizontal surface A, of area 1m² close to the Earth's surface. B) What is meant by the phrase "Gravitational potential at a point in a...

Field of what exactly? Sounds is vibrations in air molecules. Electromagnetic waves are vibrations in fields of what? Where are these fields existing? Wiki states that fields are "A field is a physical quantity that has a value for each point in space and time." Where is the physical...

Wikipedia define EM field as "a physical field produced by electrically charged objects" But there are no electrically charged objects in between cosmic entities and yet Wiki states "The electromagnetic field extends indefinitely throughout space". What am I missing here?

Hi everyone. I'm an electronics eng. student, and, during my studies, and my life outside university, I've heard several times of how electromagnetic fields could affect our body, in a way or another. There are also various resources talking about how these fields can attack cancer...

I am meeting a professor this week to see if I can work in his lab. His area of research is magnetism. In a preliminary meeting, he told me that the 'ambient' magnetic field in the lab is about twice the magnetic field of the earth. I spent about 10 minutes in the lab. There was a machine with...

1. I have heard that if you take 4 batteries and 2 non-coated wires, and run the wires + to -, with current flowing in opposing directions, with the wires in close proximity, that a magnetic field will be created between the 2 wires. Is this true? 2. Since photons have no charge, is there...

So I'm trying to figure out the electric field that is acting on a point. This point is .3 m right of a point charge with -2N/C and .8m from a point charge with +4N/C. I've drawn it out, and realize both will have an impact on this object. what the issue I'm having is figuring out a formula to...

Homework Statement The below region of space shown has uniform electric and/or magnetic fields, dependent on the conditions listed for cases A-G. Identical positively charged particles enters these regions with the same velocity. Rank the magnitude of the force on the particle just after it...

Homework Statement [/B] Charged particles with equal mass and identical initial velocities move through regions of space that may have magnetic fields. Rank the magnetic field in each case from greatest to least. For this question, fields out of the page will have positive values, while fields...

Consider a moving neutron passing by an electromagnet, will a neutron be deflected? This video seem to show that the neutron would have to be charged in order for it to move

Hello everyone, I am a junior year EEE student ( in a South Asian country ) and I will have to declare my thesis topic pretty soon. Anyway, the reason I am here is that I love Physics and want to migrate to something that is more heavy on the theoritical side. Things like particle physics...

I have been studying quantum field theory and I am currently in the Lagrangian field theory chapter in my book. Now it says that the energy momentum tensor is as follows: Tμν= [∂L/∂(∂μφ) * ∂νφ] - δμνL Note: I am using L to symbolize Lagrangian density and not just Lagrangian since the latex...

Homework Statement Please refer to attachment for solution. Can you help with the following (please refer to attached). If I understand the problem, both magnetic fields B1 & B2 need to change direction, due to the change in current (I) by replacing the positive with a negative ion. Your...

Hi, I am trying to calculate the laplacian of a scalar field but I might actually need something else. So basically I am applying reaction diffusion on a 2d image. I am reading the neighbours, multiplying them with these weights and then add them. This works great. I don't know if what I am...

I was thinking about the connection between fields and particles. For instance the scalar field Φ(x) and the field Φ(x)+a both represent the same scalar particle. Because the action ∫∂Φ∂Φdx^4 is unaltered and the propagator <0|[Φ(x)+a,Φ(y)+a]|0> is presumably the same. What about if we replace...

Homework Statement A magnetic field of 1.4 T [N] is 4.0 m wide. A very long wire crosses the field. a) If the current in the wire is 2.0 A [W]. find the magnetic force on the wire. Create a diagram. b) What will happen to the force on the wire if... i. The wire is rotated slightly in the...

I want to preface this by saying the question is a little tongue in cheek, I don't personally think that pursuing fame and glory is a good reason at all to be pursuing a career in mathematics. However, I would like to know what people here feel are the sort of traits that mathematicians who...

Homework Statement A magnetic field of 0.0200 T [up] is created in a region. a) Find the initial magnetic force on an electron initially moving at 5.00 E+6 m/s [N] in the field. b) What is the radius of the circular path? c) Make a sketch showing the path of the electron. Electron Charge =...

Homework Statement [/B] Select the answers which complete the statements below (e.g., if answer A completes the first statement, and answer B the others, enter ABBBB). A) positive B) negative C) neutral D) cannot tell A positive point charge is brought near the outside surface of a...

Homework Statement Let ##T## be a ##(1, 1)## tensor field, ##\lambda## a covector field and ##X, Y## vector fields. We may define ##\nabla_X T## by requiring the ‘inner’ Leibniz rule, $$\nabla_X[T(\lambda, Y )] = (\nabla_XT)(\lambda, Y ) + T(\nabla_X \lambda, Y ) + T(\lambda, \nabla_X Y ) . $$...

Homework Statement The tine sphere at the end of the weightless thread has a mass of .60g. It is immersed in air and exposed to a horizontal electric field of strength 700 N/C. The ball is in equlibrium in the position shown. What are the magnitude adn sign of the charge on the ball? Homework...

My textbook is going through an example on splitting fields. It asked to find a splitting field for x^4 - 6x^2 - 7 over the rational numbers. This polynomial factors to (x^2 - 7)*(x^2+1) which has roots of 7^(1/2) and i. So i figured the extension field E we are looking for is Q(i)(7^(1/2)), but...

Hi guys, So I've got a real scalar field which is the sum of the positive frequency part and negative frequency part: \phi(x)=\phi^{(+)}(x)+\phi^{(-)}(y) and I'm looking at the time-ordered product: T(\phi(x)\phi(y))=\theta(x^{0}-y^{0})\phi(x)\phi(y)+\theta(y^{0}-x^{0})\phi(y)\phi(x) for...

Homework Statement Let V be a vector space over the field F. The constant, a, is in F and vectors x, y in V. (a) Show that a(x - y) = ax - ay in V . (b) If ax = 0_V show that a = 0_F or x = 0_V . Homework Equations axiom 1: pv in V, if v in V and p in F. axiom 2: v + v' in V if v, v' in V...

I am reading about the Velo-Zwanziger problem in which particles with spin higher than 1 propagates faster than light when the particles are coupled with an electromagnetic field. In the original paper: G. Velo and D. Zwanziger, “Propagation And Quantization Of Rarita-Schwinger Waves In An...