All Questions
15
questions
1
vote
0
answers
132
views
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 ...
- 11
0
votes
0
answers
22
views
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 ...
- 75
0
votes
1
answer
86
views
What would be the Joule requirement to a railgun launch a conventional bullet at mach 7?
The railgun project from the US Naval Surface Warfare Center Dahlgren Division shoots a projectile of 3.2kg at a speed of mach 7 with 18.4 megajoules of energy.
How many joules would a railgun need to ...
- 277
0
votes
2
answers
247
views
The origin of energy density formulas in Maxwell's electromagnetism
I am looking at the derivation of Poynting theory in Electrical Engineering texts and they usually start by the two statement:
$$W_e = \int_V\frac{1}{2}(\vec{E}.\vec{D})\,\,dv$$
$$W_m = \int_V\frac{1}{...
- 126
1
vote
1
answer
49
views
Energy loss in a circuit during critical damping [closed]
I would like some intuitive explanation regarding impedance in an $RLC$ circuit.
So far, my understanding has been limited to underdamping situations where both resistance and reactance are present.
...
- 81
0
votes
1
answer
45
views
Will work be done by magnetic field?
lets discuss it in inductor topology?
A1 and A2 are contacts to the ferrite core of an inductor .DC resistance of ferrite core is of the order of milliohms,the ac resistance is quite high to avoid ...
- 11
1
vote
0
answers
842
views
Density of States (DOS) to energy graph
I am trying to find the amount of electrons in a conduction band in Si (Silicon), all I've got is a graph similar to this one:
I've tried to integrate like this:
$$ N = \int_{1}^{\infty} \frac{1}{1+\...
- 11
1
vote
0
answers
103
views
Calculating acceleration that railgun is giving to moving projectile [closed]
so my younger brother is making project for school in physics and making a basic rail gun, where the projectile is launched, using rubber band, between two aluminum rails (13.8 cm in length and 0.56cm ...
- 11
1
vote
2
answers
2k
views
An electron moving through a magnetic field [closed]
An electron, that has been accelerated from rest by a potential difference of $250\ \rm V$, enters a region of magnetic field of strength $0.12\ \rm T$. Show that speed of the electron after ...
- 121
0
votes
0
answers
56
views
Energy Stored in Electromagnetic field using Lagrangian formalism
How to we get to
$$ \int( (ɛ/2)E.E + (1/2μ)B.B ) d^{3}x $$
as the energy stored in electromagnetic field, while using the Lagrangian formalism of maxwell theory.
0
votes
1
answer
81
views
In what field is the particle $L=\frac{m}{2}\eta_{\mu\nu}u^{\nu}u^{\mu}+\frac{k\,x^3\,u^0}{((x^1)^2+(x^2)^2+(x^3)^2)^2}$
The following Lagrangian describes the behavior of a charged particle placed in a field.
$$L=\frac{m}{2}\eta_{\mu\nu}u^{\nu}u^{\mu}+\frac{k\,x^3\,u^0}{((x^1)^2+(x^2)^2+(x^3)^2)^2}$$
It is a ...
- 585
0
votes
0
answers
113
views
Can we get an explicit equation of motion?
I am looking at the following exercise:
We have an electromagnetic field. The relation between energy and momentum of a particle with charge $q$ is
\begin{equation}
\left (\frac{E-q\phi}{c}\...
- 173
0
votes
4
answers
214
views
Energy in electrostatics and magnetostatics: why do factors $\frac{1}{2}$ appear?
The electrostatic potential energy of a point charge $q$ at potential $V$ is $$U_E=q V \tag{1}$$
The electrostatic potential energy of a capacitor that has been charged with charge $q$ at potential $...
- 2,617
0
votes
1
answer
93
views
Alignment of a system in equilibrium and its potential energy
Consider a flexible free conductor which is placed near a strong long bar magnet. How will the the conductor arrange itself if current is passed through it? I asked my professor: he gave me a hint ...
- 460
0
votes
1
answer
80
views
Energy spent by motor in a period
Consider a single coil that is turning in a constant and uniform magnetic field thanks to a motor. The normal to the coil is given by:
$${\bf u}(t)=\sin (\omega t){\bf u_x}+\cos(\omega t){\bf u_z}$$
...
- 1,133