All Questions
28
questions
1
vote
1
answer
54
views
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
0
votes
1
answer
32
views
How can equilibrium state be considered even if body is an accelerated motion?
This is a question from Irodov:
Two small equally charged spheres, each of mass $m$ are suspended from the same point silk threads length $l$. The distance between the spheres $x\ll l$. Find the rate ...
0
votes
3
answers
489
views
Using Binomial and Taylor Expansions to Demonstrate Harmonic Motion [closed]
I'm doing a physics 2 self-study and I came across this question in my textbook:
A ball of mass m and charge q is constrained to move along the y axis. At the origin is a stationary charge Q. The ...
- 1
1
vote
2
answers
50
views
Equation for a rotating loop with one fixed end [closed]
This loop is rotating with angular speed $\omega$ in the counterclockwise direction in a magnetic field. I need to find the differential area element (for the purpose of finding flux). Is it going to ...
- 11
-3
votes
2
answers
168
views
Can someone explain why the moment of inertia of a circular current carrying loop is $\frac12 mr^2$? [closed]
Can someone explain why the moment of inertia of this circular current carrying ring about its diameter is $\frac12 mr^2$?
- 63
0
votes
1
answer
319
views
How come the Biot–Savart law is not applicable to derivation of magnetic field around an infinitely long, straight wire? [closed]
Context
[Edited Nov 20, 2021]
When the present question was initially asked, there was a derivation presented that lead to the wrong result. The Biot–Savart integral that I used to write the magnetic ...
- 460
0
votes
2
answers
99
views
Lorentz Force and Circular motion - What is the magnetic field causing the movement? [closed]
I am given this problem:
A particle with mass $m$ and positive charge $q$ is moving in the following path on the $x$-$y$ plane. It's path consists of semicircles as shown below. The particle's ...
-3
votes
1
answer
43
views
Problem on mechanics of bodies [closed]
I am trying to solve this problem
I thought using archimidis principle would be a way. the second body has more cavity than the first body(left body), i think, given that the 1st body will ...
- 31
3
votes
2
answers
2k
views
How to find the equation of motion of a particle in an electric and magnetic field? [closed]
I'm trying to solve a homework problem. The statement of the problem says:
"When the negatively charged plate of a parallel plate capacitor is lit up by light of a certain wavelength, electrons are ...
- 207
1
vote
1
answer
673
views
Charged particle moving in magnetic field using cylindrical coordinate [closed]
It's knowen that a charged particle take a helix trajectory in a uniform magnetic field $B =B e_z$
I tried to study this problem using cylindrical coordinate and i get that
$$F=q v ×B = m a$$
in ...
- 257
1
vote
2
answers
236
views
Non-relativistic limit of a particle in the uniform electric field
For this problem, the solution is:
$$y=\frac{m}{qE}\gamma\left[\cosh\left(\frac{qEx}{mv\gamma}\right)-1\right]$$
where $\gamma = 1/\sqrt{1-v^2}$. Here something seems to be wrong. I think that for the ...
- 1,665
1
vote
2
answers
701
views
How to calculate Centripetal force of a helical movement inside a magnetic field?
I have recently studied about the movement of a particle in a basic electromagnetic field. It circulates perpendicular to the field lines.
And the equation is then, $F= Bqv$
$B$ is the value of the ...
- 189
2
votes
3
answers
202
views
Prove a force driven by a cross product between a vector and its velocity gives a spiral movement parallel to the vector
I was given a problem in a Classical Mechanics course that went somehow like the following:
"Consider a particle of mass $m$ moving under the presence of a force $\vec{F} = k\hat{x}\times\vec{v}$, ...
- 372
0
votes
1
answer
40
views
Particle with constant momenta? [closed]
Consider a particle of mass $m$ subjected to the following potential,
$$
\vec{A}=\frac{1}{2}(\vec{B}\times\vec{r})
$$
Where the magnetic field $\vec{B}$ is constant.
Can someone prove that $\dot{...
- 297