Fields Definition and 1000 Threads

I've seen different objects described as the field in GR: the metric, the connection (and then the metric is seen as the "potential" by analogy with EM field theory), both... Could someone comment on what object should most reasonably be considered the field of the GR theory? Could for...

correct me if I am wrong but there are fundamental fields that are responsible for the forces and properties. A) how do these fields (em, higgs ect.) influence matter? B) where did they come from and when? Thanks

Hello everyone, I'm a photographer and am developing a project in which I'm needing some help. I went to some engineers friends first but they told me Physicians would be the ones who would have the answers I need. I'd like to know how can I interfere in the way my camera's sensor...

Homework Statement The Lie bracket of the fundamental vector fields of two Lie algebra elements is the fundamental vector field of the Lie bracket of the two elements: [\sigma(X),\sigma(Y)]=\sigma([X,Y]) Homework Equations Let \mathcal{G} a Lie algebra, the fundamental vector field of an...

Where can I find a picture of the magnetic field lines produced by a charged particle moving near the speed of light? Is there a formula for the strength of B and direction of field lines as v --> c? Does this equation reduce to Ampere's right hand rule for a moving charge's ability to create...

Hi All, Just wanted to know, is there any experimental or observational evidence today, that electromagnetic fields can cause spacetime curvature? Either direct or indirect?

Homework Statement 1. If the electric field is zero at a point, the potential must also be zero at that point 2. If the electric potential is zero in some region of space, then the electric field must also be zero in that region. 3. If the electric field is zero in some region of...

Studying conformal field theory, I tried to derive general expression for the commutation relations of the modes of two chiral quasi-primary fields. At first, I expressed the modes \phi_{(i)m} and \phi_{(j)n} as contour integrals over each fields, and took commutation relation. I used...

[This item has also been simultaneously posted on MHF] Polynomial Rings, UFDs and Fields of Fractions In Dummit and Foote Section 9.3 Polynomial Rings that are Unique Factorization Domains, Corollary 6, reads as follows...

Homework Statement A 1.0 m piece of wire is coiled into 200 loops and attached to a voltage source as shown. A. Find the strength of the magnetic field inside the coil if V = 100 V and R = 40 Ω. B. Which direction does the magnetic field point? C. The wire is then uncoiled and re-wrapped so...

Dear all, I don't understand why the Cosmic Microwave Background's angular distribution is considered to to a Gaussian random field initially. The rest of the analysis is roughly clear to me, COBE/WMAP/PLANCK measure the CMB Photons and show the temperature fluctuations w.r.t. the mean...

Homework Statement Let S = {(a, b): a, b \in \mathbb{Z} and b ≠ 0}. An equivalence relation "~" on S is defined by (a, b) ~ (c, d) iff ad = bc. 1) For any b \in \mathbb{Z} \setminus {0}, show that [0/b] = [0/1] and [b/b] = [1/1]. 2) For any a, b \in \mathbb{Z} with b ≠ 0, show that...

Hello, people: I've been wondering about the definition of Quantum Fields in Curved Space-times (CS). I know that, in flat space-time (Minkowski), the fields are defined as irreducible representations of the universal covering group SU(2)xSU(2) of SO(4) (which is basically the Lorentz group...

Let $f(x)\in \mathbb Q[x]$ be an irreducible polynomial of degree $n\geq 3$. Let $L$ be the splitting field of $f$, and let $\alpha\in L$ be a zero of $f$. Given that $[L:\mathbb Q]=n!$, prove that $\mathbb Q(\alpha^4)=\mathbb Q(\alpha)$. ____ Attempt: Lemma: Let $F$ be any field and $f,g \in...

A negative particle is moving in a uniform magnetic field pointing in the negative k direction. The force on the particle is -i and j. Find the x and y components of velocity. (I left out the numerical data in the question). I used F=q*v*B and in order to find the x component I used the F in the...

Would a magnetic field have any effect on the dielectric breakdown of insulators? For example, the dielectric breakdown of air is 3 Mega volts per meter at a gap of one meter; if you applied a magnetic field to that breakdown, would it help guide the electrons along the path and therefore reduce...

Hello, I have a question regarding the expansion of the Kahler potential in visible sector fields C^{\alpha} : It is usually said that the Kahler potential can be expanded as follows: K = K_{hid}(\phi,\phi^*) + K_{\bar{\alpha} \beta}(\phi,\phi^*) C^{*\bar{\alpha}} C^{\beta} + \frac{1}{2}...

Homework Statement Is it possible to create an electrostatic field E(x) (in 3 spatial dimensions x and E is a vector of course) such that i) E(x) = a × x (cross product) ii) E(x) = (a.x) b (dot product between a and x) where a,b and non-zero vectors that do not depend on time and the...

Does anybody (Jester?) know how to get WolframAlpha to plot slope fields to, say, $y'=f(x,y)$? For example, $y'=x^{2}$, and I want the slope field plotted up with $x\in[-2,2]$ and $y\in[-2,2]$. What would the actual command be? Thanks in advance!

I am seeking to understand Rings of Fractions and Fields of Fractions - and hence am reading Dummit and Foote Section 7.5 Exercise 3 in Section 7.5 reads as follows: Let F be a field. Prove the F contains a unique smallest subfield F_0 and that F_0 is isomorphic to either \mathbb{Q}...

Homework Statement Heres the question: http://imgur.com/aFJFxLa Homework Equations B = μ0/2∏r The Attempt at a Solution μ0 = 4∏*10^-7 Magnetic field = μ0/2∏r + μ0/2∏r = μ0/2∏(0.05) + μ0/2∏(0.05) = 4*10^-5 The answer is 24*10^-6 T. I need...

Homework Statement Homework Equations The Attempt at a Solution I used ∇ X F for part (a) and part (b) and found both to be ≠ 0. Thus both cases F is not conservative. I have no clue about the second part, as both arent conservative...

Homework Statement Heres the probelm: http://imgur.com/TbzJxVa Homework Equations e = kq/r^2 The Attempt at a Solution q-p Ex = (9*10^9)(4)/(0.80)^2 = 5.625*10^10 Q-p E1 = (9*10^9)(6)/(1)^2 = 5.4*10^10 Ex = E1sin45 = -3.82*10^10 Ey = E1cos45 = 3.82*10^10 P p =...

I am reading Dummit and Foote Section 9.2: Polynomial Rings Over Fields I I am having some trouble understanding Example 3 on page 300 (see attached) My problem is mainly with understanding the notation and terminology. The start of Example 3 reads as follows. "If p is a prime, the ring...

calculating electric fields due to continuous charge distributions? a question I came across doing some electric field questions, and the answer was really confusing. Homework Statement Charge is distributed along a linear semicircular rod with a linear charge density λ as in picture...

Homework Statement 1) Show that ##\underline{a} = \underline{r} f(r)## is conservative and deduce a functional form for the potential if ##f(r) = r^n##. For what value of n does the potential diverge at both ##\underline{r_o} = 0## and ##\infty##? The Attempt at a Solution I have found...

Greeting PF’rs Subject: Levitation using directed electric fields If someone had a way to take a spherical mass and pump electrons into the mass and fill many of the valence electron shells in the atoms, there would be an enormous electric field emitted by the charged mass. (Yellow sphere in...

1. Homework Statement [/b] A solid cylindrical conducting shell of inner radius a = 4.9 cm and outer radius b = 6.1 cm has its axis aligned with the z-axis as shown. It carries a uniformly distributed current I2 = 7.4 A in the positive z-direction. An inifinte conducting wire is located along...

Can unquantized fields be considered smooth curved abstract manifolds? Say free particle solutions of the Dirac equation or the Klein Gordon equation? Can quantized fields also be considered curved abstract manifolds? Thanks for any help!

Say Alice gives Bob the wave-function, a momentum eigenstate, of a charged particle. Bob then makes a local gauge transformation on the wave-function, ψ --> exp[iqθ(X,t)]ψ. Can Alice now undo the local gauge transformation with the right addition (or subtraction?) of electromagnetic...

Homework Statement A current of constant density, J0, flows through a very long cylindrical conducting shell with inner radius a and outer radius b. What is the magnetic field in the regions r < a, a < r < b, and r > b? (Use any variable or symbol stated above along with the following as...

For a magnetic fields lab I am asked to graph the data and from there, use the slope to find a certain value. For one of them, I am asked to plot the current (x) vs the magnetic field (y). The slope is supposed to give me a value, I have the slope, no clue what the value would represent...

Homework Statement Two infinite sheets of current flow parallel to the y-z plane as shown. The sheets are equally spaced from the origin by xo = 4.2 cm. Each sheet consists of an infinite array of wires with a density n = 16 wires/cm. Each wire in the left sheet carries a current I1 = 2.3 A in...

Is it possible for a spherically symmetric field, on all of R^3, to have a divergence of 0? (assuming the field is nonzero) Relevant equation: F=f(ρ)a (a is a unit vector of <x,y,z>) and f(ρ) is scalar fxn, and ρ = lal

Let $K=\mathbb{Q}[\omega]$ where $\omega^2+\omega+1=0$ and let $R$ be the polynomial ring $K[x]$. Let $L$ be the field $K(x)[y]$ where $y$ satisfies $y^3=1+x^2$.Which is the integral closure of $R$ in $L$, why?

Hey Pf.. I am trying to understand Lenz's law, but somehow it doesn't make sense. In my book there is some checkpoints execise to test wheather you've understood what you read about, one those checkpoints looks like this. http://snag.gy/NCNLh.jpg I do understand why the current in...

Author: Roger Harrington Title: Time-Harmonic Electromagnetic Fields (IEEE Press Series on Electromagnetic Wave Theory) Amazon Link: https://www.amazon.com/dp/047120806X/?tag=pfamazon01-20 Prerequisities: Undergraduate degree in Electrical Engineering or Physics, with appropriate...

Homework Statement A particle of mass m and charge -q moves in a circular orbit of radius R about a fixed charge Q. The angular frequency for the orbit is given by \omega_0^2 = \frac{qQ}{4 \pi \epsilon_0 m R^3} A uniform magnetic field of magnitude B in a direction perpendicular to the plane...

Homework Statement An ion of mass m and charge q is accelerated from rest through a voltage of ΔV. It then enters a magnetic field. Determine the mass of the ion in terms of the measurable quantities: q, ΔV, (B^→) , and x. Homework Equations The Attempt at a Solution m =...

We know that a direct current generates a magnetic field which surrounds the wire in circular patterns (right-hand rule). However when alternating current runs through a wire, no actual electrons are transported from one end to the other but rather they "vibrate" so to speak and transmit this...

A lot of below might be a question of semantics however it helps to understand better, I am a novice: 1. What's the difference between a field and a dimension? A field is present at all points in time and space, ...so is a dimension. why don't we call/label a field as a dimension? 2. or...

Momentum and magnetic fields are both vector quantities. If two bodies with the precise mass and speed collide head on (θ = 0), then momentum is conserved (they come to a complete stop) and energy is conserved (the kinetic energy is changed to other forms). What then happens in the case of...

You place a conductor in an electric field. The charges inside the conductor will relocate, to form an opposing electric field which cancels the outside field, making the field inside the conductor zero. However, surely there's a limit to how big an opposing field the charges in the...

This is a really basic question, but... Say I have a massive scalar field obeying the Klein-Gordon equation linearized about flat space, \partial_t^2 \phi + (k^2 + m^2)\phi = 0. This has solutions \phi \sim e^{\pm \sqrt{k^2 + m^2}t} and the sound speed should be \omega_k/k =...

Homework Statement At which location will the electric field between the two parallel plates of a charged capacitor be the strongest in magnitude? a. near the positive plate b. near the negative plate c. midway between the two plates at their ends d. midway between the two plates nearest...

A gravitational field and a magnetic field both decrease in strength at the distance squared. They are two totally different forces so why the correlation?

I have taken my Gauss surface as the front of the shape, with E_1 coming through uniformly. I get the right answer for the charge inside the shape, but I'm unsure about b. I imagine a situation that I've drawn could be possible, but I've never seen it before, so I do not know. I'm thinking that...

Homework Statement z+ up with E field, y to the right, x out of the page with B field particle released from rest at (0,0,0) with only initial y velocity y=(E/B)t or initial y=(E/2B)t Homework Equations can you suggest a good differential equations text...

After writing this, I realized that I really have no idea what I'm going on about. Mainly, I don't understand the significance of it being an insulating object. I gather this means the charge is distributed uniformly throughout the object, rather than at the surfaces, but I don't know how I can...

It is asked to find the electric flux through a "gaussian" sphere which has a point charge (-3 microcoloumbs) enclosed with the radius of 0.2 m ... I can shortcut this and use Flux= q Enclosed / e0.. However, i want the other approach using the formula Flux = ∫ E da... I know that E is constant...