Potential Definition and 1000 Threads

Potential generally refers to a currently unrealized ability. The term is used in a wide variety of fields, from physics to the social sciences to indicate things that are in a state where they are able to change in ways ranging from the simple release of energy by objects to the realization of abilities in people. The philosopher Aristotle incorporated this concept into his theory of potentiality and actuality, a pair of closely connected principles which he used to analyze motion, causality, ethics, and physiology in his aPhysics, Metaphysics, Nicomachean Ethics and De Anima, which is about the human psyche. That which is potential can theoretically be made actual by taking the right action; for example, a boulder on the edge of a cliff has potential to fall that could be actualized by pushing it over the edge. Several languages have a potential mood, a grammatical construction that indicates that something is potential. These include Finnish, Japanese, and Sanskrit.In physics, a potential may refer to the scalar potential or to the vector potential. In either case, it is a field defined in space, from which many important physical properties may be derived. Leading examples are the gravitational potential and the electric potential, from which the motion of gravitating or electrically charged bodies may be obtained. Specific forces have associated potentials, including the Coulomb potential, the van der Waals potential, the Lennard-Jones potential and the Yukawa potential. In electrochemistry there are Galvani potential, Volta potential, electrode potential, and standard electrode potential. In the
thermodynamics, the term potential often refers to thermodynamic potential.

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  1. S

    Why does the PE of particles during steam condensation decrease?

    The answer says it decreases but shouldn't it increase? according to the kinetic model, KE accounts for particle vibrations. PE accounts for the attractive forces between particles. Since condensation means gas -> liquid, it means the particles become closer and hence the attractive forces...
  2. per persson

    Potential in spherical shells

    In r<a the potential is V_o. I don't understand why in a<r<2a, V(r)=V_o-\int^r_a E*dl. I would write V(r)=\int^r_a E*dl+\int^2a_\infty E*dl I dont know how to write math symbols here but I wrote question here...
  3. du_768

    How can the electric potential be constant between two points in a wire?

    Homework Statement: circuits - terms Relevant Equations: - How exactly can the electric potential be constant between two points in a wire; (assuming that it is electron current); if the electron is moving from a region of high electric potential to a low electric potential because of the...
  4. kal8578

    I Change of coordinates in a potential energy field

    Hello, I am having some confusions in what should be basic pointwise Newtonian mechanics, and would like to get some help with that. It is all about changing coordinates in potential energies. Let us start by considering a point particule in a 2d world with an axis x (left-right) and an axis z...
  5. tellmesomething

    Electrostatics and current problem with 3 metallic balls

    Theres a picture of the circuit attached. I did not understand how to start the problem since we dont know the distance between the terminal A and the sphere to write the absolute potential at terminal A. So I looked at the solution and im afraid I dont understand it at all. The teacher took...
  6. BuggyWungos

    Why does electric potential energy increase if you move against the field?

    My understanding of this question is that, if you have a proton standing against a positive electric field, and move it in the opposite direction of the field, you're putting in work and therefore should have greater electric potential energy. But that idea breaks down when you consider a...
  7. Heisenberg7

    B E. Potential Energy: Uniformly Charged Hollow Sphere and Point Charge

    I was doing a problem with this one detail. It says that the electric potential energy of an uniformly charged hollow sphere and a point charge is (at the surface of the hollow sphere; both positive): $$U = k \frac{q_1 q_2}{r}$$ I guess this assumes that the hollow sphere is a point charge. Now...
  8. C

    I The potential on the rim of a uniformly charged disk

    This comes from Griffiths' Electrodynamics and is problem 2.51 or 2.52, the disk has a surface charge density and my usual approach to solving these problems is to pick an area element and find a way to create a vector to the point(s) at which the potential is evaluated at. I sent a picture of...
  9. tellmesomething

    What is taken as datum level for the following absolute potentials?

    We take out "formulas" for electric potential from the relation $$V=\int E.dx$$ Some general formulas are : For a hollow sphere : ##\frac{Q} {4π\epsilon_0 x}## when x>R, x =distance of that point from the center And the problem is we just input the distance in sums to calculate absolute...
  10. A

    Conservation of Momentum Problem - Mechanical and Kinetic Energies

    I'm confused on this problem, as I feel they state two completely contradictory things in the explanation of how to solve it. The first statement that I feel contradicts the second is this: "We can see that the bullet’s speed v must determine the rise height h. However, we cannot use the...
  11. keyzan

    Harmonic potential exercise with perturbation theory

    Hello there, I'm training with some exercises in view of the July test, so I will post frequently in the hope that someone can help me, since the teacher is often busy and there are no solutions to the exercises. A particle of mass m in one dimension is subject to the potential: ##V(x) =...
  12. L

    I Finite potential well transmission coefficient

    In the last page of this image, the formula for the transmission coefficient, i'm not sure exactly what it means. The page says there is no reflection when the sine term is 0 cuz T=1), but for scattering states E>0 anyways? So won't it always pass through? Or is there a chance for a particle...
  13. kated

    How to find the potential of a field that has regions of non-zero curl

    We know that in electrostatics, there is path independency for line integral of E, so E is a conservative field and thus we have E=-gradV. Integrating this from ro(reference point of our choice) to the point r we are studying, along a random path, we get the solution of the above equation...
  14. srnixo

    Gauss' law and the potential V (plane layer case)

    Here is the exercise: And these are my attempts: This is for the first question about the electric field. (I know I'm missing the drawing, which is a drawing of the plane layer of thickness 2e with a cylinder on it as a GAUSS SURFACE ). As for the second question, I'm not sure about it, so I...
  15. dannolul

    The value of the spring constant k that I calculate seems too high

    I expanded ET1=ET2 to get (Total energy at top) 1/2mv^2+mgh = 1/2kx^2 (Total energy at bottom) Rearanged i got k = (mv^2+2mgh)/x^2 so [(73)(20)^2+2(73)(9.8)(52)]/0.465^2 =479137.945N/m
  16. J

    A I'm trying to follow the proof given in Box 5.3 of MCP (Thorne/Blandford)

    I'm trying to follow the proof given in Box 5.3, page 235, of the MCP book regarding the Van der Waals grand potential. It seems to me that there is a missing factor (2l−1)!/(l−1)! in the last term of Equation (8). What am I doing wrong?
  17. E

    Electromagnetism problem: Merging of 2 charged drops of mercury

    I originally thought that this problem was simple, and it still seems like it is, but there are conflicting solutions and I don't know which is correct. So I first solved for R1 and R2 using V=kQ/r where R1 is 0.514 and R2 is 0.54. My original thought was volume is conserved so V1 + V2 = V3 and...
  18. amandela

    Elastic Potential Energy - Positive or Negative?

    So I understand that I have to integrate the negative of the force function to get the change in PE. I get -(20x^2 - 2x^3) and when I evaluate it from 0 to 2, I get -64N. But, of course, the change is positive. What am I missing? Thank you.
  19. Lok

    B Gravitational potential energy, a thought experiment

    Hi PF, long time no see. Hope you are all well. Recently I have come into a mental conundrum of a cosmological physical nature. After doing some napkin calculations about the energy of celestial bodies and transforming them into mass via E=mc^2 I've found that said energy is by no means small...
  20. Quantum Psi Inverted

    Gravitation Potential Energy -- Questions about calculating the sign of GPE

    I believe that this is due to context of application, but now, I'm starting to doubt myself. For example, a helicopter lifting itself has positive PE change. I really don't intuitively understand how this works. Can someone kindly explain this to me?
  21. MatinSAR

    Mistake in "Foundations of Electromagnetic Theory"?

    The book wanna show how to find potential of a dielectric. The problem arises when it uses a vector identity. Still there is no problem. My problem is that I cannot understand why ##\rho_P= -div P##? I think it should be ##-div' P##. The book is wrong? In next page it uses ##-div'## In...
  22. MatinSAR

    Force field in spherical polar coordinates

    Picture of question: Part (a) : ##\nabla \times \vec F = 0## so a Potensial exists. I don't have problem with this part. Part (b) : what I've done : First experssion is 0 because ##\theta = \dfrac {\pi} {2}##. I don't know how to integrate over ##\theta ## when it is a constant.
  23. haruspex

    B Symmetry regarding induced potentials?

    A homework thread, https://www.physicsforums.com/threads/point-charge-with-very-thin-metal-sheet-along-a-spherical-surface.1057702/, references https://arxiv.org/pdf/1007.2175.pdf. There is an uncharged conductor and a point charge. In the paper referenced, ##\bar\phi_y(x)## is defined as the...
  24. H

    I Force of an Electron on a Potential Wall?

    I've been looking at a practice test for an introductory class in quantum physics, and I've found a really weird question. It asks for an estimation of the force that an electron exerts on the walls of a box of known length during a collision. This seems like an entirely nonsense thing to ask...
  25. AntonioJ

    Potential associated with a conservative force field F

    Given the potential energy, the force is obtained as F = -∇U(r). A conservative force field F is associated with a potential f by F = ∇f. Does the first expression arise from this last one? If so, with -∇U(r), would one obtain the electric field E instead of the force F?
  26. deuteron

    Why Does a Particle Not Remain at x(t)=0 in a Negative Quartic Potential?

    This question is from Collection of Problems in Classical Mechanics by Kotkin & Serbo, here, the answer is given as the following: However, the graph of ##-Ax^4## looks like: so shouldn't the trajectory be just ##x(t)=0##?
  27. G

    Particle moving from one potential to another

    Attaching the image of the problem as an image. Somehow text is not copied from the book. Somehow, I can't imagine the picture in my head. We can do it in 2D plane. I know, it mentions the solution, but need to see the drawing, otherwise, my logic fails. I thought that maybe, first half space...
  28. L

    Question about the integral used to calculate the voltage between two points

    ^^
  29. PhysicsTest

    Understanding of Voltage potential

    I am bit confused with voltage potential terminology again to basics When it is referred as Voa it is Voltage of "o" wrt "a". Is it correct? But other major question is as per the document I would have written KVL as Voa - I1 * Z = Vn. I am really confused with notation used.
  30. ab200

    What Am I Doing Wrong in Calculating Potential on a Grid?

    Looking at the image, I see that due to symmetry, the bottom-left negative charge and the bottom-right positive charge cancel out, leaving me with a triangle around the center. I'm not entirely sure how to solve for potential at the origin specifically, but I believe that the potential energy of...
  31. V

    Potential difference between 2 points in a capacitor circuit

    In the given circuit, a transient current will flow and when this current finally stops at equilibrium, the charges ##q_1## and ##q_2## are assumed to deposit at the capacitor plates as shown below. The dashed line indicates an isolated system that will have it's total charge conserved. If I...
  32. T

    I Callan-Symanzik equation for Effective Potential

    Hey all, I am looking equations (13.24),(13.25) in Peskin & Schroeder's QFT book and I am confused about how they change from the Callan-Symanzik equation for the Effective Action to the Effective Potential. I thought the relation for constant ##\phi_{cl}## was ##\Gamma[\phi_{cl}] = -(VT)\cdot...
  33. Grelbr42

    I The Potential of Back-to-Back Photons: an Experiment

    In some cases, photons can be produced in "back to back" (BTB) conditions. For example, electron-positron annihilation produces two photons, each at 0.511 MeV, with equal and opposite momentum. Or pretty close, up to the original velocities of the electron and positron. Start with a source of...
  34. milkism

    Method of Images, combination of an infinite plane and a hemisphere

    Problem: I have done part a) in spherical polar coordinates. For part b) I thought it would be just: $$\sigma = -\epsilon_0 \frac{\partial V}{\partial r}$$ But I got confused by "You may want to use different coordinate systems .." So I assume partial derivative w.r.t to r is the spherical...
  35. S

    Experiment about diode related to temperature and potential difference

    (a) I know some of the apparatus needed for the experiment, such as DC power supply, ammeter, voltmeter, maybe rheostat. But I don't know how to change the temperature of diode. What is the correct and safe way to change the temperature of diode? Thanks
  36. yucheng

    I Electric potential and potential difference

    Electric potential = "absolute potential" Textbooks usually connect both ends of two capacitors, of different voltages, in parallel. What would happen if we only connect one end of the capacitors? Perhaps we would have to solve for Maxwell's coefficients of potential for these two cases (to...
  37. E

    Electron encountering metal surface (1D Step potential)

    I am struggling with how to go about this; in particular, I'm not sure I understand what state is being alluded to when Ballentine says "For an electron that approaches the surface from the interior, with momentum ##\hbar k## in the positive ##x## direction, calculate the probability that it...
  38. S

    I Potential energy of spin anti-alignment

    Hello everybody, I consider two electrons that have enough kinetic energy to reach their respective classical electron radius. This would be: 2.0514016772310431402e-13 J The corresponding speed is v = 287336682 m/s. The electric field is E = \frac{k_{e}}{R_e^2} = 1.8133774657059088443 ×...
  39. Z

    MIT OCW, 8.02 Electromagnetism: Potential for an Electric Dipole

    Here is a depiction of the problem a) The potential at any point P due to a charge q is given by ##\frac{kq}{r}=\frac{kq}{\lvert \vec{r}_s-\vec{r}_P \rvert}##, where ##r## is the distance from the charge to point P, which is the length of the vector difference between ##\vec{r}_s##, the...
  40. S

    A Moire potential depth from continuum model

    Dear All, I am trying to calculate the moire potential depth of transition metal dichalcogenide system. I have attached supporting material obtained from one of the thesis. Here they have describe the continuum model hamiltonian for TMDs homobilayer. My question is how to obtain the moire...
  41. jerry222

    Electrodynamics - finding potential of a non conducting shell

  42. S

    Rate of loss of potential energy

    I got answer for (a), which is 0.51 m For (b), loss of potential energy = 35 x 9.81 x 0.51 = 175 J Rate of loss of potential energy = 175 J / 1 s = 175 W But the answer key is 80 W. Where is my mistake? Thanks
  43. haziq

    How Can I Solve for the Travel Time of a Particle in a Potential?

    I’ve been trying to solve this for ages. Would really appreciate some hints. Thanks
  44. Darmstadtium

    B Conversion of Potential Energy: Sound or Heat?

    When a coin is dropped from a certain height and collides with a glass surface, is the majority of the potential energy converted to sound or heat? And how would one determine this as I only hear the sound and cannot measure the significant change in temperature?
  45. K

    What is 4-Vector Potential Transformation under Gauge Fixing?

    What is 4- vector potential transformation under Gauge fixing ?
  46. C

    A Multiparticle Relativistic Quantum Mechanics in an external potential

    It is often argued that Dirac Equation is not valid as relativistic quantum mechanics requires the creation of antiparticles. But, there are also some arguments that suggest otherwise. For example, I saw Arnold Neumaier's website on this that there are multiparticle relativistic quantum...
  47. Muu9

    Kinetic Energy / Potential Energy / Total Energy question

    W_ext is the external work done on B and C, which is 12 J Delta K_tot is the internal work, which is the work done by A on B plus the work done by A on C Delta K_tot = 5 Solving for \Delta U, we find that the change in potential energy is 7 J This answer says otherwise...
  48. Jake357

    Calculating Distance Travelled Using Electric Potential

    I only could calculate the distance travelled by each body, by making the difference between the initial and final electric potential work equal to the work of friction done by the 2 bodies.
  49. Jake357

    How to Correctly Solve for the Minimum Distance Between Two Electrons?

    I tried to make the kinetic energy of the first electron equal to the electric potential work. mv^2/2=ke^2/d We have to solve for the minimum distance between them: d=2ke^2/mv^2=5.05*10^-10 m The force is: F=ke^2/d^2=9*10^-10 N, which is not correct.
  50. G

    I 4-Current vector potential transformation under Gauge fixing

    I am given an initial vector potential let's say: \begin{equation} \vec{A} = \begin{pmatrix} g(t,x)\\ 0\\ 0\\ g(t,x)\\ \end{pmatrix} \end{equation} And I would like to know how it will transform under the Lorenz Gauge transformation. I know that the Lorenz Gauge satisfy...
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