All Questions
Tagged with electromagnetism homework-and-exercises
1,551
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I am trying to derive an expression for the magnetic field of charged particles travelling at significant fractions of speed of light [closed]
I tried using lorentz transformation , which gives me correct answer for speed of light c but when i try to input any other values nearby c it becomes a constant
B = 10-7 . q/r² ( (v - u)/ 1- uv/c²)
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Force acting on an infinite wire with current inside a magnetic medium
I've recently stumbled on an electromagnetics problem that I don't quite understand.
There is an infinite wire carrying current I that is placed inside a medium with magnetic permittivity μ1. At a ...
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What are the operators here and how are these formulas derived? [closed]
In (23), are grad and div some kind of scalar operators comparing to $\nabla$ and $\nabla\times$? because tbh I dont know how $\text{curl}(\mu^{-1}\text{curl}\textbf{A})$ turns into $\text{div}\mu^{-1}...
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What book should I read to learn about the magnetocaloric effect
I am trying to study the magnetocaloric effect for a project but I can't find any good resources that deeply talk about it.
Could you make any good recommandation to learn the basics about this effect ...
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1
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Magnetic moment of a paramagnetic cylinder
I am currently struggling with a problem where I have to calculate the magnetic moment $M$ of a
cylinder of radius $R$ and height $h$ made up of a paramagnetic material (aluminium) and under a ...
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Vector potential of Weird loop
I have to calculate the vectorpotential of a current flowing through the loop at the origin:
where the current is given by $I(t)=kt$ for some $k>0$.
Given equations
$$\mathbf{A} = \frac{\mu_0}{4\...
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Why is charge $q$ chosen as the variable of integration when converting from summation to integral form in electric field calculations?
If we have several point charges $q_1, q_2, q_3, \cdots$, and their distances from a test charge $Q$ are respectively ${\imath}_1, {\imath}_2, {\imath}_3$, $\cdots$, then the electric field intensity ...
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Current sensitivity in transformer scheme with SQUID
I've tried to determine the maximum current sensitivity in this transformer scheme but I'm not sure if my solution is valid. I need to find the relation between the current in the input transformer ...
2
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1
answer
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How to derive $\partial^{\nu}F^{\mu\alpha} + \partial^{\alpha}F^{\nu\mu} + \partial^{\mu}F^{\alpha\nu}=0$ for the Electromagnetic field tensor? [closed]
The problem says to show that
$$\partial_{[\mu}F_{\alpha\nu]}=F^{\mu\alpha, \nu} + F^{\nu\mu,\alpha} + F^{\alpha\nu,\mu}=0$$ stems from Maxwell equations.
I haven't been able to find this anywhere on ...
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Where am I going wrong when obtaining the Hamiltonian density for the electromagnetic field?
I'm trying to verify that the Hamiltonian density for the classical electromagnetic field is equal to the energy density. But the electric field is disappearing and only the energy density of the ...
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Question about Fourier-coefficients in Griffith's Problem 3.15 (Electrodynamics) [closed]
I am having some trouble with problem 3.15 from Griffith's Electrodynamics. It states the following:
A rectangular pipe, running parallel to the $z$-axis (from $-\infty$ to $+\infty$), has three ...
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1
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27
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General Form of the Biot-Savart Law for anywhere on the $x$-Axis [closed]
This question is beyond me, and I have very little direction for solving it. I understand that the component of $\ B $ perpendicular to the $x$-axis is 0, and that the component parallel along the $x$-...
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Need help identifying missing boundary condition in charge transport problem
The system I am considering consists of a conducting liquid sandwiched between two electrodes.
The electrodes supply a constant flux of electrons $J_{ext}$.
In the liquid there are also uncharged ...
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Charged pendulum and a fixed point charge
!My set-up is the following: i have an iron bolt suspended on a string next to an electromagnet, of which I steadily increase the voltage and thereby the magnetic field. Supposing the force is linear ...
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Perturbation of central field potential
i`d like to consider system with Coulomb potential: $U = -\frac{\alpha}{r}$ and constant magnetic field.It is easy to write Lagrangian function:
$$ L = \frac{m}{2}(\dot{\rho}^2 + \rho^2\dot{\phi}^2) + ...
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Equations of motion for Lagrangian of scalar QED [closed]
I really would appreciate your help with this exercise.
I have the Lagrangian for scalar electrodynamics given by:
$$\mathcal{L}=-\frac{1}{4}F_{\mu\nu}(x)F^{\mu\nu}(x)+(D_\mu\varphi(x))^*(D^\mu\varphi(...
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Effect of incident angle on wavelength of transmitted wave for normal polarisation?
In my electrodynamcis assignment I'm being asked to derive the wavelength of a normally polarised wave transmitted through a glass/air interface as a function of $n_1$ (the refractive index of the ...
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What does "90 degrees ahead of phase" mean in inductance problems?
I've been working on this homework problem and I have determined that the induced EMF on the right coil is sin(x-90). However, I do not understand what "ahead of phase means." When I graph ...
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No displacement current should be produced in this case, but it does!
Considering this question, i think the concept used is wrong coz direction of E produced due to changing magnetic field is along the circular loop(tangential at each point on loop) of radius r. While ...
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Effects of dielectric on force between charged bodies?
The electrostatic force between the plates of a charged isolated capacitor remains unchanged when dielectric fills whole space between plates.
But when we take 2 isolated point charges in a dielectric ...
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Coilgun projectile force calculation
Please excuse me if I am completely wrong because I am a 9th grader but I hopefully am able to explain briefly about my problem. I was trying to create a function to calculate the Force of an iron ...
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Path of a relativistic charge due to a (nearly) infinitely massive charge [closed]
Suppose we know the position, velocity of a charge at time $t=0$ and its rest mass is also known. It is attracted by a (nearly) infinitely massive known opposite charge which is at rest and always be ...
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Is there a $H$-field formed by a uniformly moved, charged ball?
Imagine a charged ball with surface charges. Let it travel with a constant velocity $v$.
Imagine a point outside the ball. Since the charge is moving, there is a electric displacement displacement ...
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2
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Maxwell's equations with differential form formalism
I've been reading Sean Carroll's book on GR and I stumbled upon an exercise on EM using $p$-forms. I think I've solved the problem correctly but I am having problems with my answers. I'll provide the ...
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Derivation of Maxwell's equations using Lagrangian formalism [duplicate]
Some time ago, I read in Landau's Theoretical Physics Course you could derive Maxwell's equations using the Lagrangian formalism, and I find this to be exciting. Unfortunately, I don't have access to ...
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Field Momentum of a Toroid with a point charge at its center
I´ve been solving the following problem and I need some guidance. The problem asks to calculate all the components of the field momentum of a circular toroidal coil of mean radius a and N turns with a ...
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What is the relationship between the energy absorbed and reemitted by an atom?
What is the relationship between the energy absorbed and emitted by an atom with the model of Lorentz?
In the Lorentz model of an atom, we have that, using the effective cross-sections we might get ...
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Direction of propogation of a EMW [closed]
If let say i have an EMW given by- (Note the difference between $k$ and K)
B(x,y,z)=$B_0sin[(x+y)\frac{K}{√2}+wt]\hat k$
i got confused in 2 different outcomes when i wanted to find out the direction ...
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Covariant derivative property
I am trying to demonstrate this propertie
$$
\not{D}^2= \mathcal{D}^\mu \mathcal{D}_\mu-\frac{i}{4}\left[\gamma^\mu, \gamma^\nu\right] F_{\mu \nu}
$$
where $\not{}~$ is the Feynmann slash, and $D_\mu ...
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How can I estimate the force of an electromagnet?
I am doing an experiment on electromagnetism, basically I am just testing the pulling force of an electromagnet using a newton meter with a magnetic hook and seeing how the pulling force changes as i ...
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