Tagged Questions
0
votes
1answer
37 views
The potentiality of the electric field
Could you, please, explain me using just words why electric the field is potentially? I know the proof using integral: $A = \int_{12}q\overrightarrow{E}\overrightarrow{dr} = ...
0
votes
2answers
54 views
Electron in an infinite potential well
Does this problem have any sense?
Suppose an electron in an infinite well of length $0.5nm$. The state of the system is the superposition of the ground state and the first excited state. Find the ...
1
vote
0answers
36 views
tricky electric potential [closed]
I have this question: $q_1$ is a Uniformly Charged long Wire(inf in z axis) with $\lambda$ (charge per unit length).
In (0,0,0) I have A very long conducting cylinder of radius a (also inf in z axis). ...
-1
votes
0answers
48 views
Electric Potential and Electric field intensity [closed]
A hollow charged metal sphere has a radius r . If the potential difference between it's surface and a point at a distance 3r from the center is V, then the electric field intensity at a distance 3r ...
0
votes
1answer
51 views
Electric field and potential [closed]
An oil drop of radius 0.70mm containing a charge of -4.8 x 10-19 C is placed in an electric field if the drop remain stationary at the point find the magnitude and direction of electric field ...
0
votes
0answers
43 views
Wave equations for two intervals at Potential step
Lets say we have a potential step as in the picture:
In the region I there is a free particle with a wavefunction $\psi_I$ while in the region II the wave function will be $\psi_{II}$.
Let me ...
0
votes
0answers
33 views
Is it easier to determine the number of states with raising/lowering operators or using scattering?
A particle is bound by
$$V(x) = \begin{cases}\infty,& x <0 \\ \frac{-32\hbar^2}{ma}, & x\le a \\ 0, & x \le a\end{cases}$$
a) how many states are there?
i'm attempting ...
0
votes
1answer
95 views
Energies and numbers of bound states in finite potential well
Hello I understand how to approach finite potential well (I learned a lot in my other topic here). However i am disturbed by equation which describes number of states $N$ for a finite potential well (
...
2
votes
2answers
278 views
Plotting $\psi$ for finite square well potential
Lets say we have a finite square potential well like below:
This well has a $\psi$ which we can combine with $\psi_I$, $\psi_{II}$ and $\psi_{III}$. I have been playing around and got expressions ...
1
vote
1answer
106 views
Finite potential well - transcendent equation for even solutions
I have a finite square well like the one on the picture below:
I have done some calculations on it and got a transcendental equation for even solutions which is like this:
$$
...
1
vote
1answer
143 views
Finite, square, potential well
Lets say we have a finite square well symetric around $y$ axis (picture below).
I know how and why general solutions to the second order ODE (stationary Schrödinger equation) are as follows for ...
0
votes
1answer
223 views
Non conducting charged planes
I have two parallel non conducting charged planes with opposite charges $6\mu C/m^2$, area $A = 3m^2$ and distance between the planes $d = 0.004 m$. I know the potential between these two planes is ...
0
votes
1answer
63 views
Electric charge and the distance
The strength of an electric field is: $E = 200\ \mathrm{N/C}$
The potential (of the test charge) is: $V = 600\ \mathrm{V}$
$\epsilon_r=1$
I need to calculate the distance between this point and the ...
1
vote
2answers
60 views
Wavefunction restrictions of odd potentials
So I was just reading back through Griffiths' "Introduction to Quantum Mechanics" and solving some of the problems for practice. There is a nice one (problem 2.1c for those playing at home) where you ...
1
vote
2answers
456 views
Particle in infinite potential well which is doubled in size at $t_0$
I am currently studying for an exam in Quantum Mechanics and came across a solution to a problem I have trouble with understanding.
The Problem:
A Particle sits in an infinite potential well ...
1
vote
1answer
154 views
Electric field of a flat metal plate and a point particle
I'm currently studying electric potential, and I'm having trouble with one of the problems on my homework:
A) A point particle with charge $+q$ is on the x-axis at a distance $d$ from the origin, ...
1
vote
1answer
262 views
( Legendre Generating Function) Off axis Electric Potential from an insulated disk
An insulated disk, uniform surface charge density $\sigma$, of radius $R$ is laid on the $x,y$ plane. Deduce the electric potential $V(z)$ along the z-axis. Next consider an off axis point $p'$, ...
3
votes
1answer
550 views
Electric Potential of a Charged Sphere
Problem Consider a sphere with radius $R$, and with a charge distribution $\rho(r)=\rho_0r$. Using Poisson's equation, calculate the electric potential inside and outside the sphere.
Solution I don't ...
1
vote
1answer
317 views
Schrödinger function: Separable wave function with even potential function of x
I have done the Problem 2.1 in Griffiths' quantum mechanics,
and it seems not making sense to me.
What if the wave function isn't symmetric at all?
Then obviously the proof doesn't work. The ...
1
vote
2answers
212 views
Find the quantity of charge - given potential function
A potential function is given by $V(r)=\frac{Ae^{-\lambda r}}{r}$ Find charge density and hence charge.
I first took the gradient of potential to get $\vec{E}(r)=\frac{Ae^{-\lambda ...
1
vote
1answer
264 views
Force exerted on potential wall
A particle bound in an infinite potential wall at $x=0$ will apply a force on the wall. For a plane wave and imagining it as a fluid bouncing off the reflection wall at $x=0$, find the force in terms ...
1
vote
2answers
493 views
Barrier in an infinite double well
I am stuck on a QM homework problem. The setup is this:
(To be clear, the potential in the left and rightmost regions is $0$ while the potential in the center region is $V_0$, and the wavefunction ...
2
votes
2answers
560 views
Electric potential of sphere
(a) I am a little confused about this part. The point at A to B isn't radial. The electric field is radially outward, but if I look at the integral
$$\int_{a}^{b}\mathbf{E}\cdot d\mathbf{s} = ...
-5
votes
1answer
370 views
Lennard-Jones potential - equilibrium [closed]
If I have Lennard-Jones potential, how can I calculate equilibrium?
$$ U(r)=\epsilon \left ( \left (\frac{r_m}{r} \right )^{12}-2 \left (\frac{r_m}{r}\right )^6 \right ) \ $$
0
votes
1answer
342 views
Bound states for sech-squared potential
I'm working on an introductory qm project, hope somebody has the time to help me (despite the length of this post), it will be highly appreciated.
My goal is to determine the bound states and their ...
0
votes
0answers
86 views
Calculating Electric potential [closed]
A charge Q is distributed over two concentric hollow spheres radii a and b (b>a) such that their source charge densities are equal. Find the potential at the their common center
0
votes
0answers
197 views
Potential of two concentric spheres not charged [closed]
In the problem we got two concentric spheres with radius $a$ and $b$ respectively. the spheres are connected by thin wire and both spheres are thin. at distance $R$ from the center they put a charge ...
1
vote
0answers
93 views
An electron is subjected to an electromagnetic field using the canonical equations solve
So I was given the following vector field:
$\vec{A}(t)=\{A_{0x}cos(\omega t + \phi_x), A_{0y}cos(\omega t + \phi_y), A_{0z}cos(\omega t + \phi_z)\}$
Where the amplitudes $A_{0i}$ and phase shifts ...
4
votes
4answers
2k views
Infinitely charged wire and Differential form of Gauss' Law
I have tried calculating the potential of a charged wire the direct way. If lambda is the charge density of the wire, then I get
$$\phi(r) = \frac{\lambda}{4 \pi \epsilon_0 r} \int_{-\infty}^\infty ...
1
vote
1answer
75 views
Formula for potential for 2 coaxial tubes
Could someone remind me of the formula for potential function for a system consisting of 2 coaxial tubes maintained at a fixed potential difference and the in between medium has uniform conductivity ...
1
vote
1answer
979 views
How to calculate the charge and the potential across a charged capacitor charging an uncharged capacitor?
Initially, there is a single capacitor $A$ attached to a power source that charges it to a certain voltage $V$. Once it is charged, it is instantaneously removed and placed in a circuit with an ...
2
votes
1answer
805 views
How to solve Schrodinger Equation - Tunnelling
I have to solve analitically the Schrodinger equation in one-dimension with a barrier of potential (tunnel effect):
$$ih \frac{d}{dt} U(x,t) = \left[ \left(-h^2 \frac{d^2}{dx^2} \right) + q V(x) ...
0
votes
2answers
290 views
The energy of electric interaction between these dipoles?
I'm a physics tutor. This is not a homework problem. I'm unable to solve this problem.
The energy of electric interaction between these dipoles will be:
Choose the correct answer from:
I tried ...
2
votes
1answer
424 views
How is capacitance defined for three concentric spheres?
If we have a configuration of metal concentric spheres (each of negligible thickness) of radii $r_1,r_2,r_3$ respectively and $r_1<r_2<r_3$, and we are given the potentials of the spheres to be ...
0
votes
1answer
55 views
Potential at a point
What is the electric dipole moment of the charge distribution with $q$ at $(0,0,1)$, $q$ at $(0,0,-1)$ and $-2q$ at $(0,0,0)$? I would think that it is $\vec{0}$ by the definition ...
-1
votes
2answers
140 views
Show that the energy levels of a particle in a specific potential are $E_n=(n+\frac{1}{2})h\omega-\frac{1}{2}\frac{F^2}{m\omega^2}$ [closed]
A particle of mass m moves on the x-axis under the influence of the potential
$$V(x)=\frac{1}{2}m\omega^2x^2+Fx$$
Can anyone help me, using Schrödinger's equation in one dimension that the energy ...
0
votes
1answer
80 views
How to calculate the potential of the ball? [closed]
Consider 2 metals ,the smaller sphere has a radius of a carry +Q charges,what is the potential at the surface of the smaller sphere?
2
votes
1answer
761 views
How to calculate time evolution of a wave function in an 1D infinite square well potential?
A particle in an infinite square well has an initial wavefunction
$$\psi (x,0) ~=~ Ax(a-x) \qquad \mathrm{for}\qquad 0\leq x\leq a.$$
Now the question is to calculate $\psi (x,t)$.
I have ...
2
votes
2answers
698 views
What is the potential difference between point X and point Y?
Here is the problem:
In the above figure I want help on finding the potential difference between X and Y.
It is getting quite confusing due to the battery in the middle. I found the current in both ...
