# potential

1. ### Determine the Electrical potential at a given point

A rod with a circular center in the middle (which causes the rod to change direction by 90 °) has an evenly distributed linear charge density 𝜆 of electrons along the entire rod. Determine the electrical potential of the red dot in the figure below which is at the center of the circular round...
2. ### I Electrical potential of a thin wire in an E field

Assume that an infinite metallic plate A lies in the xy-plane, and another infinite metallic plate B is parallel to A and at height z = h. The potential of plate A is 0, and the potential of plate B is constant and equal to V. So, there is a uniform electrostatic field E between plates A and B...
3. ### I Electrostatics: sign of the potential

The final result will only differ in its sign, but this is crucial. Having a positively, radially oriented electric field $\textbf{E}$, I understand that the sign of the integral should be positive ($- (- A) = A$), but it is not! How and why is this the case? A line integral where the...
4. ### A The Laplacian of the potential q*exp(-r)/r

Hello, I have a problem where I'm supposed to calculate the charge distribution ρ. I need to calculate it by applying the Laplacian operator to the potential Θ. The potential is the function: q*exp(-αr)/r I found on the internet that for this type of potentials I cannot just apply the...
5. ### Python Lennard Jones potential (analytic and numerical solutions)

Summary: I'm starting a project in my lab where I need to make a program using the Lennard-Jones potential equation in Python. There also needs to be an output graph with the program showing the function. I'm having problems finding workable codes (I keep running into errors) that I could use...
6. ### B Retarded and advanced potentials

"of the two types of solutions which the Maxwell equations yield for the wave equation, the retarded and advanced potentials, only the retarded field seems to have a physical meaning," let's start please with basic (and detailed as possible for the knowledgable layman! p.s-which equation is...
7. ### What happens when one of two cocentric spherical shells is grounded?

Hi! I need help with this problem. When the outer shell is grouded, its potential goes to zero, $V_2=0$ and so does it charge, right? $-Q=0$. So the field would be the one produced by the inner shell $E=\frac{Q}{4\pi\epsilon_0 R_1^2}$. When the inner shell is grounded, I think that...
8. ### I Morse Potenials Energy eigenvalues

I know the eigen value of energy in a Morse potential is Evib= ħωo(v+ 1/2) - ħωoxe(v+ 1/2)2 but is this the same for every Morse potential, given that the masses μ of the diatomic molecules are the same? The two potentials are these:
9. ### How to find the period of small oscillations given the potential?

I first found the equilibrium points taking the derivative of the potential. $U'(x)=U_0 a\sin(ax)$, and the equilibrum is when the derivative is 0, so $U_0 a\sin(ax)=0$ so $x=0$ or $x=\pi/a$. Taking the second derivative $U''(x)=U_0a^2 \cos(ax)$ I find that $x=0$ is a minimum point...
10. ### Why a DC power supply doesn't have a voltage with respect to ground?

I see that DC power supply have voltage between it's + & - and its 24V. However, there is no voltage with ground. I don't understand - if device's "point" has some potential, why doesn't it give some voltage with ground (which has ~0 potential) I tried this with phoenix contact...
11. ### Electric potential at the edge of a thin charged circular plate

My question might sound stupid to you but please clear my confusions. I'm taking an circular arc like element on the plate. That arc has a radius of 'r' (AB) and the radius is inclined at an angle 'θ' with OA (∠OAB). The area between arc of radius r and r+dr is dA. dA = 2θr.dr The charge on...
12. ### A position of stable equilibrium, and the period of small oscillations

I tried by taking the derivative of the potential to find the critic points and the I took the second derivative to find which of those points are minimum points. I found that the point is $x=- a$. I don't understand how to calculate the period, since I haven't seen anything about the harmonic...
13. ### The potential between a cone and a plate

Homework Statement [/B] There is a conducting cone with angle α placed so that its vertex is normal to an electrically grounded plate, but electrically insulated from the plate and kept at a constant potential V. Find the potential V and the electric field in the region between the cone and the...
14. ### System of charges

Homework Statement Two charges, $-q_1$ and $q_2$ are fixed in the vacuum and separated by a distance $a$. What should be the velocity $v$ of a particle with mass $m$ and charge $q$, travelling from an infinitely far point along the line which unites $q_1$ and $q_2$ in order to...
15. ### Potential at center of sphere of radius R and charge -Q

Homework Statement What is the potential at the center of the sphere relative to infinity? The sphere is dielectric with uniform - charge on the surface of the sphere. Homework Equations $k=\frac {1}{4\pi\epsilon_0}$ $V=\frac {KQ}{r}$ The Attempt at a Solution If the distance r=0 it would...
16. ### A Examples of a Lagrangian

Assuming generlized variables, q, we have a Lagrangian in mechanics as the kinetic energy, K, minus potential energy, U, with a dependency form such that L(q,dq/dt) = K(q, dq/dt) - U(q) Can someone provide examples of Lagrangians in other disciplines?
17. ### I Question on the work done while charging up a capacitor.

So the work done when charging up a capacitor is $dW=VdQ$ However, when we add a charge $dQ$ to the capacitor, $V$ also changes accordingly, so I was wondering why the work done wasn't written as $dW=VdQ+QdV$ (one that also takes into account t he change in $V$). Thanks in advance.
18. ### I What happens to the Electrical Potential the closer we are to a point charge?

So I have been wondering: The potential for a point charge at the origin, is described as: (Using the reference point at infinity): V=1/(4πε) * q/r My question is, what happens to this Potential the closer we are to the point charge, and so the closer we would get, the Potential seems to go...
19. ### Method of Images Problem

Homework Statement The z = 0 plane is a grounded conducting surface. A point charge q is at (0,0,a), and charge 4q at (0,-2a,a). Calculate the potential in the region z > 0. Homework Equations V=∑kq/r The Attempt at a Solution [/B] Use the method of images. V1 = kq/r+ + kq/r-...
20. ### Gravitational Potential Reference Point

Can someone please show that calculation of gravitational potential energy at a point R+h from the centre of the earth by choosing the centre of the earth to be at zero potential. Here R is the radius of the earth and h is not very small wrt to R
21. ### A few questions regarding Neutral Objects

1. Homework Statement Hello, I'm learning electricity and I'm having a few conceptual questions regarding the subject ( especially about neutral objects ) which I'm unsure of the answers and I'd be happy if someone could help me: 1. Is the charge density of a neutral object ( doesn't matter...
22. ### I Particle in a potential well

Let's suppose I have a potential well: $$V(x)= \begin{cases} \infty,\quad x<0\\ -V_0,\quad 0<x<R\\ \frac{\hbar^2g^2}{2mx^2},\quad x\geq R \end{cases}$$ If $E=\frac{\hbar^2k^2}{2m}$ and $g>>1$, how can I calculate how much time a particle of mass $m$ and energy $E$ will stay inside...
23. ### I Finite square well bound states

Let's suppose I have a finite potential well: $$V(x)= \begin{cases} \infty,\quad x<0\\ 0,\quad 0<x<a\\ V_o,\quad x>a. \end{cases}$$ I solved the time-independent Schrodinger equation for each region and after applying the continuity conditions of $\Psi$ and its derivative I ended up with...
24. ### I Potential energy loss related to force applied?

How can I calculate the loss of potential energy when forces are applied but no motion in the system occurs? Here's an example: Let's say I build a battery operated car that is set to drive forward, but I put it right in front of a wall. It attempts to drive forward, but instead it just pushes...
25. ### Capacitance of a sphere

Homework Statement Assume a conducting sphere has a radius of 3400km with an electric field of 100 V/m at it's surface. a) Calculate total charge of sphere. b)Calculate potential at the surface using infinity at reference point c) Calculate capacitance of the sphere using the result of a or b...
26. ### Trajectory of a proton as it moves between the plates

Homework Statement Homework Equations What makes the shape circular/ parabolic? what determines the direction? The Attempt at a Solution Because the furthermost plate is positive, the proton would be repelled towards the screen, so i or iii. How do I know the shape?
27. ### I Potential $V$ and potential energy $E_{pot}$?

Hi, I know that in an elecric field the potential energy $E_{pot}$ is equal to the potential $V$ times the charge $E_{pot}=q V$. Here my problem: I know that the potential energy of a spring is $E_{pot}= \frac{1}{2}kx^2$. In my theoretical physics book i read also that the potential is...
28. ### Projectile motion, potential and kinetic energy

Homework Statement Homework Equations The Attempt at a Solution 1/2mv^2=10 1/2m(ucos60)^2=10 1/2mu^2/4=10 mu^2=80 what to do now?
29. ### Problem with line integrals for electric potential

Homework Statement I have a problem understanding the equation $$\Delta V = -\int_{a}^{b} \vec{E} \cdot d \vec{l}$$ In the case of a parallel plate capacitor whereby the positive plate is placed at $z=t$ while the negative is at $z = 0$, my integral looks like \Delta V = -\int_{0}^{t}...
30. ### B Electric Field of a Line of Charge

If the electric field of a line charge at a distance 'a' is µ/2Π ε0a (µ is linear charge density), then the potential at that point should be µ/2Π ε0 (since potential = electric field x distance). This means that the potential is constant at every point around the line of charge. Hence, this...