All Questions
259 questions
-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 ...
0votes
0answers
52views
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 ...
0votes
1answer
37views
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 $x$-...
1vote
1answer
60views
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 ...
-2votes
1answer
104views
Where is this circular loop attracted? [closed]
A circular loop carrying current "I" in anti-clockwise direction is placed between two straight and parallel wires each carrying current I. Ignoring the force of the straight wires on each ...
- 121
1vote
1answer
130views
Magnetic Scalar Potential of Infinite Wire
While working on a question about magnetic scalar potential, I encountered a challenge. The question posits that the magnetic scalar potential, denoted as $\phi$, takes the form $\phi = -\frac{I}{2\pi}...
3votes
3answers
126views
Finding the vector potential
$$\nabla\times\mathbf{B}=\nabla\times\left(\nabla\times\mathbf{A}\right)=\nabla\left(\nabla\cdot\mathbf{A}\right)-\nabla^2\mathbf{A}=\mu_0\mathbf{J}\tag{5.62}$$ Whenever I try to work this out and ...
- 220
0votes
1answer
59views
Why can the current in this region be represented as this formula?$I_{in}=I-I\frac{r^2-b^2}{c^2-b^2}$ [closed]
An air coaxial transmission line has a solid inner conductor of radius a and an outer conductor of inner radius b and outer radius c. Find $\vec B$ as a functions of radial distance r. The region in $...
0votes
3answers
744views
Should a wire loop moving through a constant rectangular magnetic field directed perpendicular to it's motion have zero induced current in the middle?
Suppose we have a loop of copper wire moving perpendicularly through a constant finite rectangular magnetic field directed into the screen . When the loop enters the field, the induced current would ...
1vote
1answer
351views
Magnetic field in the left focus of an ellipse current loop
given a 2D ellipse in 3D space parametrized as $x(t)=a\cos{t}$, $y(t)=b\sin{t}$, I would like to find the magnetic field at point $(-c,0,0)$, $c=\sqrt{a^2-b^2}$. (The current $I$ is running counter-...
- 51
0votes
0answers
56views
Calculating Magnetic Vector&Scalar Potential
I want to calculate the magnetic scalar and vector potentials for an infinite axial current density given as \begin{equation} J(r,\varphi) = \frac{I}{R} \delta(r-R) \sin\varphi \cos\varphi \bf{\hat{k}...
- 125
1vote
1answer
54views
Why does $\vec v \times \vec B$ change to $\vec a \cdot \vec B$? [closed]
I was doing a question where the solution said this: $$\vec F = q (\vec v \times \vec B)$$ $$m \vec a= q (\vec v \times \vec B)$$ $$ \therefore \vec a \cdot \vec B = 0 $$ $$(x\hat i + 7 \hat j) \...
- 29
0votes
1answer
230views
How to derive the magnetic field at a point a distance $x$ from the center of the axis of a circular loop of radius $R$ carrying current $I$? [closed]
Question: What is the magnetic field at a point a distance $x$ from the center of the axis of a circular loop of radius $R$ carrying current $I$? I was given the answer $\frac{\mu_0}2 \frac{IR^2}{(x^...
- 103
0votes
1answer
231views
In the question given below, why the length for calculating reluctance is taken by those dotted lines?
The question is as follows: For the core shown in Fig. 3.20, it is required to produce a flux of 2 mWb in the limb CD. The entire core has a rectangular cross section of 2cm × 2cm. The magnetizing ...
0votes
2answers
225views
How to determine the electric and magnetic fields from $*F=q\sin \theta d\theta \wedge d\phi$?
I have the 2-form $*F=q\sin \theta d\theta \wedge d\phi$, how can I determine the eletric and magnetic fields from that? I have tried wrtting F in the vector potential form for them finding the ...
- 378
