All Questions
Tagged with homework-and-exerciseselectromagnetism
1,563 questions
-7votes
0answers
50views
A beautiful question on inductance, but my answer is coming wrong [closed]
A cylindrical coaxial cable consists of an internal solid conductor of radius "a" with external thin walled conductor of radius "4a".The current distribution over the cross section ...
0votes
1answer
58views
Calculation of the torque on a current-carrying loop of wire is off by a factor of $-2$
The magnetic moment of a current-carrying wire loop $L$ is: $$ \boldsymbol\mu = \frac I2\oint_L\mathbf{r} \times \mathrm{d}\mathbf{r}. $$ Also $\boldsymbol\tau=\boldsymbol\mu \times \boldsymbol B $, ...
-6votes
0answers
77views
Feynman propagator for a massive vector field $A^\mu$ [duplicate]
Considering the Proca equation, how can one show that the Feynman propagator in momentum space is: $$\tilde G(k)^{\mu\nu}=i \frac{-g^{\mu\nu} + \frac{k^\mu k^\nu}{m^2}}{k^2-m^2+i\epsilon}$$ ...
- 1,750
0votes
2answers
41views
A question concerning infinite resistor ladder circuit [closed]
I just do not understand how the solution even makes sense. The question asks me to find the equivalent resistance between terminals $A$ and $B$. The solution assumes the resistance between terminals ...
-4votes
2answers
178views
Reason why magnetic field lines never intersect [closed]
Assertion (A): Magnetic field lines around a bar magnet never intersect each other. Reason (R): Magnetic field produced by a bar magnet is a quantity that has both magnitude and direction Is the ...
1vote
2answers
90views
How is inductive reactance of a pure inductor that is connected to an ideal DC source defined?
While solving some previous year mock questions for my upcoming final exams, I came across this question that has perplexed me for the last couple of hours: If a pure inductor of inductance $L$ is ...
- 343
2votes
1answer
86views
Analytical Model for Joule Heating in a Straight Wire?
I'm looking for an analytical model that describes the steady-state (or time dependent) temperature as a function of position along a straight wire (e.g. nichrome) due to Joule heating when a current ...
- 1,416
1vote
2answers
110views
Efficiently deriving Maxwell from Euler-Lagrange equations
From the Lagrangian density for electromagnetism $$\mathcal{L} = -\frac14 F_{\mu\nu} F^{\mu\nu}$$ and the Euler-Lagrange equations $$\frac{\partial \mathcal{L}}{\partial A_\alpha} = \partial_\mu \frac{...
- 3,267
1vote
0answers
85views
Polarisation and dispersion relation for electromagnetic waves with complex $k$
I'm attempting to answer this past exam question: The monochromatic plane wave solution for the electric field is given as: $$ \begin{equation*} \mathbf{E}(\mathbf{r}, t)=\mathbf{E} \exp [i(\mathbf{k}...
- 11
-2votes
1answer
43views
Deflection of an alpha particle between 2 bar magnets with opposite poles facing each other [closed]
The question I ask is where will this alpha particle deflect? Towards the south or north pole or inwards towards the plane of the paper or outwards from it? This is from a Indian 10th grader.
0votes
0answers
57views
Inductance of two infinite conducting cylinders forming an infinite loop with current flowing through
I recently came across the following question: Two infinite long conducting cylinders with radius $a$ are parallel apart and the separation between the central axes of the cylinder is $D$. There is a ...
1vote
2answers
128views
Lorentz invariants of electromagnetic tensor
I`m stuck in what seems like a very basic derivation. I`m having my very first contact with the covariant formulation of Electrodynamics, and I want to show that $$\epsilon^{\mu\nu\rho\sigma}F_{\mu\nu}...
1vote
1answer
66views
Tangential electric field
Given at an interface $z=0$ : $$E = (30 \hat{x} + 20 \hat{y} + 10 \hat{z})\cos(\omega t)$$ And the direction of propagation is $z$. I want to find the normal electric field $(E_N)$ and the tangential ...
- 167
1vote
0answers
35views
What difference would the following change make to the readings of the voltmeters?
I asked a couple of days ago the question that you can find in Would the two voltmeters measure the same value? I didn't get an answer to that question. However, I want to make a small modification to ...
- 1,046
0votes
1answer
127views
Would the two voltmeters measure the same value?
I made this problem up. The rod is moving to the left in a uniform magnetic field, would the two connected voltmeters give the same reading? My analysis says yes. They would since the induced emf in ...
- 1,046
