Fields Definition and 1000 Threads

From the Maxwell Equations we know that there are four boundary conditions for an electromagnetic wave crossing an interface between two dielectric media. For the TE polarisation state, these conditions give us that E_{i} + E_{r} = E_{t} B_{i}\,\cos\theta_{i} - B_{r}\,\cos\theta_{r} =...

That is to say, how does time behave in a region of space where multiple gravitational fields cancel out their accelerating effects? I understand that time "slows down" in a gravitational field, but does this depend on the actual presence of the field, or instead the actual net acceleration...

Homework Statement A charged particle moves in a region of space where there is a uniform magnetic field B (in the z direction say,) and a uniform electric field E in the yz plane. Write the equations of motion for the particle. Then solve them, taking for initial conditions (at t=0) x=y=z=0...

Hi. I am currently an undergrad following a physics major, and I am in the final year of my course.I am planning to continue on with grad studies and wants to know the most demanding(subject wise and salary wise) paths in physics.(Ex: astrophysics,astronomy,condensed matter physics,medical...

Hello! I've made a lot of research about measurement of high magnetic fields - such us 1T - 2T and I can't find sensors for this range. I'm looking for a hall sensor with which I will be able to measure 1T magnetic field with good accuracy - about 0.1 mT. Do you know about anything like that...

1. Why is Earth's South Pole called its North Pole? Why hasn't it been changed to make it more scientifically accurate? 2. Why are the North Poles of other planets defined relative to Earth's 'North' Pole? Why isn't it based upon the actual direction of the planet's magnetic field?

So I know if you move a charge in a magnetic field it induces voltage and hence a flow of charge is created which is current. ( Please correct me if I'm wrong). But that's pretty basic right. However, I'm having trouble understanding the use of split rings in the functioning of a motor. I would...

Over the next decade, and few decades, which branches/ fields of physics will experience tremendous growth? I'm wondering what field I'd want to "specialize in" or focus in and could use some of your guy's opinion.

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...

Homework Statement What are the associated peak amplitudes of the E and H fields if sunlight has a maximum intensity of 1400 W/m2 on the earth’s moon? Homework Equations I = <s> = 1/2 c ε0E2The Attempt at a Solution I = <s> = 1/2 c ε0E02 1400 = (1/2)(3*108)(8.85*10-12)(E02) 1400 /...

Hello, I'm reading through section 6.2.2 of https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-013-electromagnetics-and-applications-spring-2009/readings/MIT6_013S09_chap06.pdf on page 157. I understand all the math, but I have a conceptual questions that I don't seem to...

in theories such as SUSY and MSSM where there are 5 Higgs fields, do the other higgs fields also impart mass? and how exactly is it determined which of the additional higgs fields impart mass on which particles? do the other higgs field impart mass on other higgs bosons? wouldn't there be...

This book is too expensive for me to buy. Can someone share ebook/ pdf?

Is it possible to have a magnetic field of a any geometry we want, or there are only few types of geometries that can be achieved with permanent magnets and electromagnets? If the former, how do we produce a magnetic field of specific geometry? For example, can the magnetic field be cylindrical...

Homework Statement This is the question: An electron at rest of mass 9.11 × 10−31 kg is accelerated through a potential difference of 350 V. It then enters some deflecting plates of 50 V with dimensions as shown. Calculate the distance x (deflection of the electron) (Charge on an electron is...

Homework Statement Homework Equations N/A The Attempt at a Solution Im not sure if I've done this right because it seems too little for 6 marks. I have arrows coming from the north to the south end for the magnet's magnetic field. I have arrows going counter clockwise around the conductor...

If I have a lagrangian which has terms of the form ##\Psi^{\dagger}_\mu \Psi^\mu## then I can decompose the n complex ##\Psi## fields into 2n real fields by ##\Psi_\mu = \eta_{2\mu+1} + i\eta_{2\mu}##. When I look at the lagrangian now it seems to have SO(2n) symmetry from mixing the 2n real...

https://arxiv.org/pdf/1705.07188.pdf Equation 5 in this paper states that $$\frac{\partial F}{\partial p_i} = 2Re\left\lbrace\frac{\partial F}{\partial x}\frac{\partial x}{\partial p_i}\right\rbrace$$ Here, p_i stands for the i'th element of a vector of 'design parameters' \mathbf{p}. These...

Homework Statement Homework Equations ##V=V^u \partial_u ## I am a bit confused with the notation used for the Lie Derivative of a vector field written as the commutator expression: Not using the commutator expression I have: ## (L_vU)^u = V^u \partial_u U^v - U^u\partial_u V^v## (1)...

Homework Statement An Electron enters a parallel plate apparatus that is 8cm long and 4cm wide. The electron has a horizontal speed of 6*10^7 m/s. The potential difference between the plates is 6*10^2 V. Calculate the electrons velocity as it leaves the plates. (ans. 6*10^7 m/s [E 3.3° N])...

I am designing a device, which will utilize an electric field. The question I have run into is whether or not the current is treated as the charge enclosed for Gauss' Law, or if there's another way I would calculate it. Also, am I correct that the voltage of the circuit would be different than...

Homework Statement Can there be a point in space where there is an electric potential but not electric field? Can there be a point in space where there is an electric field but no electric potential? Explain you answer. What would the electric field lines look like if the electric field was...

In a transformer, the primary coil has a current running through it which creates a magnetic field. Then this field induces a current in the secondary coil. That induced current creates a magnetic field exactly opposite the inducing magnetic field. This might be an obvious question, but that...

In the Peskin&Schröder's QFT book there's an exercise that's about a pair of scalar fields, ##\phi_1## and ##\phi_2##, having the field equations ##\left(\partial^{\mu}\partial_{\mu}+m^2 \right)\phi_1 = 0## ##\left(\partial^{\mu}\partial_{\mu}+m^2 \right)\phi_2 = 0## where the mass parameter...

Homework Statement Question attached: Homework Equations [/B] Using the result from two fields that ## T(\phi(x) \phi(y))= : \phi(x) \phi(y) : + G(x-y)## Where ##G(x-y) = [\phi(x)^+,\phi(y)^-] ## ## : ## denotes normal ordered and ##\phi(x)^+ ## is the annihilation operator part , and...

I'm having trouble choosing my advanced papers. So I want to know which fields are saturated and which are the hot ones right now.

It is said that light needs no medium. But light is just an excitation of the electromagnetic field in QFT. This excitation presumably propagates within that field at the speed c and once that excitation has left a point in space, the field has settled down to 0 energy again, analogous to pond...

Homework Statement A proton moves with constant velocity in a certain region of gravity-free space.Which one of the following conclusions is valid? A)There must be no electric field or magnetic fields in the region. B)There could be an electric field without any magnetic field. C)There could be...

I've posted this here because I think it might be related to the absoluteness of acceleration and rotation. I've been educating myself on the Faraday Disk and was very surprised by one aspect of it. If we have a solid metal disk mounted on a shaft with two electrical brushes contacting the...

I am reading Anderson and Feil - A First Course in Abstract Algebra. I am currently focused on Ch. 45: The Splitting Field ... ... I need some help with an aspect of the proof of Theorem 45.6 ... Theorem 45.6 and its proof read as follows: https://www.physicsforums.com/attachments/6701At...

I am reading Anderson and Feil - A First Course in Abstract Algebra. I am currently focused on Ch. 45: The Splitting Field ... ... I need some help with an aspect of the proof of Theorem 45.6 ... Theorem 45.6 and its proof read as follows: At the start of the proof of Theorem 45.6 we read...

I am reading Anderson and Feil - A First Course in Abstract Algebra. I am currently focused on Ch. 45: The Splitting Field ... ... I need some help with some aspects of the proof of Theorem 45.5 ... Theorem 45.5 and its proof read as follows: In the above text from Anderson and Feil we...

I have this question which I need to solve . But I am unable to. Suppose I have a current ring of radius R and current I (constant). at a distance x from the centre of the ring, I have a iron disk (radius r and thickness t) present in the plane of the ring. This disk will be attracted to the...

I am reading Anderson and Feil - A First Course in Abstract Algebra. I am currently focused on Ch. 45: The Splitting Field ... ... I need some help with some aspects of the proof of Theorem 45.4 ... Theorem 45.4 and its proof read as follows: My questions on the above proof are as...

I am reading Anderson and Feil - A First Course in Abstract Algebra. I am currently focused on Ch. 45: The Splitting Field ... ... I need some help with some aspects of the proof of Theorem 45.4 ... Theorem 45.4 and its proof read as follows: My questions on the above proof are as...

I am reading David S. Dummit and Richard M. Foote : Abstract Algebra ... I am trying to understand the example on Finite Fields in Section 13.5 Separable and Inseparable Extensions ...The example reads as follows: My questions are as follows: Question 1In the above text from D&F we read the...

I am reading David S. Dummit and Richard M. Foote : Abstract Algebra ... I am trying to understand the example on Finite Fields in Section 13.5 Separable and Inseparable Extensions ...The example reads as follows: My questions are as follows: Question 1In the above text from D&F we read the...

Griffiths introduction to electrodynamics talks about how electric potential is always continuous and electric fields are continuous except in the case of a surface charge density. This seems fair assuming you can have a continuous surface charge Density, but in the real world, these densities...

I am reading both David S. Dummit and Richard M. Foote : Abstract Algebra and Paul E. Bland's book: The Basics of Abstract Algebra ... ... I am trying to understand separable polynomials ... ... but D&F and Bland seem to define them slightly differently and interpret the application of the...

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! Can someone explain to me how does a scalar field changes under a Lorentz transformation? I found different notations in different places and I am a bit confused. Thank you!

I am reading Dummit and Foote, Chapter 13 - Field Theory. I am currently studying Section 13.4 : Splitting Fields and Algebraic Closures ... ... I need some help with an aspect of Example 3 of Section 13.4 ... ... Example 3 reads as follows: In the above text by Dummit and Foote, we read...

I am reading Dummit and Foote, Chapter 13 - Field Theory. I am currently studying Section 13.4 : Splitting Fields and Algebraic Closures ... ... I need some help with an aspect of Example 3 of Section 13.4 ... ... Example 3 reads as follows: In the above text by Dummit and Foote, we read...

Hi, I'm currently investigating magnetic fields/their cause. This has inevitably led me to learn all about electrons. Here I want to post my understanding on electron 'spin' so people can correct me if I'm wrong/help others get a better understanding. So I watched this YouTube video for...

Homework Statement Homework EquationsThe Attempt at a Solution These are problem 5.1 (b) and the solution. I understood the gap between each loop is 1/N, but why does each loop have vertical direction current amount of I/N ?? [/B]

I am a little confused about terminology when it comes to extension fields. In my textbook, E is a field extension of F if F is a subfield of E. This is understandable. However, in proving that all polynomials have a zero in an extension field, ##F[x] / \langle p(x) \rangle##, where ##p(x)## is...

I am a teacher and I can't work this one out. I am trying to answer (a). I have only included the further parts of the question (b, c and d) so you can see why some parts of the question are included. A single positively charged particle, mass 4.6 x 1027 kg, enters a 4.0 T magnetic field into...

I am reading Dummit and Foote, Chapter 13 - Field Theory. I am currently studying Theorem 3 [pages 512 - 513] I need some help with an aspect the proof of Theorem 3 ... ... Theorem 3 on pages 512-513 reads as follows: In the above text from Dummit and Foote, we read the following: " ...

I am reading Dummit and Foote, Chapter 13 - Field Theory. I am currently studying Theorem 3 [pages 512 - 513] I need some help with an aspect the proof of Theorem 3 ... ... Theorem 3 on pages 512-513 reads as follows: In the above text from Dummit and Foote, we read the following: " ... ...

What is the intuitive reasoning for requiring that a Lagrangian describing a free-field contains terms that are at most quadratic in the field? Is it simply because this ensures that the EOM for the field are linear and hence the solutions satisfy the superposition principle implying (at least...