What is Electric potential: Definition and 1000 Discussions

The electric potential (also called the electric field potential, potential drop, the electrostatic potential) is the amount of work energy needed to move a unit of electric charge from a reference point to the specific point in an electric field with negligible acceleration of the test charge to avoid producing kinetic energy or radiation by test charge. Typically, the reference point is the Earth or a point at infinity, although any point can be used. More precisely it is the energy per unit charge for a small test charge that does not disturb significantly the field and the charge distribution producing the field under consideration.
In classical electrostatics, the electrostatic field is a vector quantity which is expressed as the gradient of the electrostatic potential, which is a scalar quantity denoted by V or occasionally φ, equal to the electric potential energy of any charged particle at any location (measured in joules) divided by the charge of that particle (measured in coulombs). By dividing out the charge on the particle a quotient is obtained that is a property of the electric field itself. In short, electric potential is the electric potential energy per unit charge.
This value can be calculated in either a static (time-invariant) or a dynamic (varying with time) electric field at a specific time in units of joules per coulomb (J⋅C−1), or volts (V). The electric potential at infinity is assumed to be zero.
In electrodynamics, when time-varying fields are present, the electric field cannot be expressed only in terms of a scalar potential. Instead, the electric field can be expressed in terms of both the scalar electric potential and the magnetic vector potential. The electric potential and the magnetic vector potential together form a four vector, so that the two kinds of potential are mixed under Lorentz transformations.
Practically, electric potential is always a continuous function in space; Otherwise, the spatial derivative of it will yield a field with infinite magnitude, which is practically impossible. Even an idealized point charge has 1 ⁄ r potential, which is continuous everywhere except the origin. The electric field is not continuous across an idealized surface charge, but it is not infinite at any point. Therefore, the electric potential is continuous across an idealized surface charge. An idealized linear charge has ln(r) potential, which is continuous everywhere except on the linear charge.

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  1. G

    Electric potential of hollow conducting sphere

    Homework Statement A charge conducting hollow sphere and a point charge with radius of sphere and distancestors between their centers Homework Equations [/B] 3. The atempt at a solution I am unable to find the potential of Shere in presence of external point charge
  2. W

    Electric Potential V inside nonconducting sphere with cavity

    Homework Statement A nonconducting sphere of radius r_2 contains a concentric spherical cavity of radius r_1. The material between r_1 and r_2 carries a uniform charge density rho_E(C/m^3). Determine the electric potential V, relative to V=0 at r= infinity, as a function of the distance r from...
  3. KayDe

    Electric Potential Energy Problem

    Homework Statement Two Charged Objects (Q1= -9.0nC & Q2= 15nC) are fixed in place on the +x-axis. The first charge is 12 cm to the left from the origin the other is 12 cm to the right from the origin. A proton is moved from the origin to a position on the +y-axis 9.0 cm from the origin. a)...
  4. 8008jsmith

    Electric Potential Energy and micro-joules

    Homework Statement A uniform electric field of 16.9 N/C is directed in the positive x direction. If a charge of -2 micro-coulombs moves 2.2 meters in the negative x direction, how much does the electric potential energy change in micro-joules? Homework Equations ΔEPE = qEd The Attempt at a...
  5. J

    Can Electric Potential Be Understood On Intuitive Level?

    There are two situations with electric potential that confuse me. They're the spots midway between two point charges. If the charges are the same, then the electric field is zero and a test charge would not move if placed there. How can there then be electric potential in that spot? If...
  6. H

    Electric Potential Over Non-Uniform Rod

    Homework Statement The thin plastic rod shown in the figure has length L = 18.0 cm and a nonuniform linear charge density λ = cx, where c = 14.5 pC/m2. With V = 0 at infinity, find the electric potential at point P1 on the axis, at distance d = 5.10 cm from one end. Figure is attached...
  7. A

    Determine The Speed of a Charge at a given point

    Homework Statement Given: The electric potential function: V= 3x^2 + 2xy +(y^2)z + 20 a) A 4 coulombs, 2kg charge is released from the origin. Determine the speed of the charge at (1,1,-1) Homework Equations Kinetic Energy= 1/2 mv^2 The Attempt at a Solution I tried to use the fact that the...
  8. V

    Electric field and electric potential

    Homework Statement [/B] Homework Equations dV = -EdX[/B] The Attempt at a Solution Well I was trying to think about the relationship between E and V. So I believe the two V and E are co dependent. So in a situation where the distance and the potential are not changing then wouldn't V...
  9. T

    Electric potential at center of semicircle

    Homework Statement A total charge Q is uniformly distributed on a thread of length L. This thread forms a semicircle. what is the potential at the center? (assume V=0 at large distances) Homework Equations V = -∫Edl E = kQ/r^2 The Attempt at a Solution V = - ∫Edr = -E∫dr = -Er = - kQr/r^2 =...
  10. S

    Where between two charges does voltage = 0?

    Homework Statement If Q1 in the above figure is twice Q2 and both are positive, where can a point of zero potential be found?Homework Equations V = kq/r The Attempt at a Solution I know that eventually I'll have to set it up so that kq/r = kq/r, but my problem is, how do you know where this...
  11. P

    In which region is it possible for electric potential = 0?

    Two charges that are shown: I (4uC) II (-2uC) III In which regions all the line connecting the charges is it possible for the electric potential to be zero? 1. Homework Statement They are 0.01m apart Homework EquationsThe Attempt at a Solution I understand that the 4uC charge and...
  12. T

    Superposition principle for potential?

    Homework Statement A solid, conducting sphere of radius "a" and charge -Q is concentric with a spherical conducting shell of inner radius "b" and outer radius "c". The net charge on the shell is +3Q. Take the zero of electric potential to be at some point at infinity. a.) Use Gauss's law to...
  13. T

    Potential difference between wire and ground

    Homework Statement A long, straight power line is made from a wire with radius ra = 1.0 cm and carries a line charge density λ = 2.6 μC/m. Assuming there are no other charges present, calculate the potential difference between the surface of the wire and the ground, a distance of rb = 22 m...
  14. H

    Pointlike charge - electric potential

    This is my first time using a website like this, so I sincerely apologize if I'm posting in the wrong spot, I'm just in a bind/frustrated with this seemingly easy problem. Homework Statement What is the electric potential at a point 0.80 m away from a point charge of 3.5m C? Homework...
  15. carllacan

    Electric potential on concentric spheres

    Homework Statement A metallic sphere at ##\phi = 0 ## is surrounded by a spherical layer with charge density ##\rho ##. Find the potential at every point...
  16. I

    Clarifying Electric potential energy

    I read somewhere online that according to Coulomb's law, in the context of an atom, the potential energy of an electron is proportional to the distance (squared) between the positive and negative charges, this however doesn't show up in the actual eq F = kq1q2/r^2 I thought about it in terms of...
  17. G

    Electric potential of a cube of 8 point charges

    Homework Statement Find the Electrostatic potential energy of a cubical configuration of point charges. (One charge on each corner of a cube). Each of the charges is 3.00e and the edge of the cube is 3 cm. Homework Equations U = kqQ/r The Attempt at a Solution I'm pretty sure I understand...
  18. J

    Two charged nonconducting sphere shells

    Homework Statement One of two nonconducting spherical shells of radius a carries a charge Q uniformly distributed over its surface, the other a charge -Q, also uniformly distributed. The spheres are brought together until they touch. What does the electric field look like, both outside and...
  19. P

    Electric potential at surface sphere problem?

    Homework Statement Homework Equations The sphere is positively charged and appears to have its charge concentrated at its centre. Potential V is calculate to be 285V The Attempt at a Solution The charge induced on inside of box is negative. THe potential is less. It is said that it's being...
  20. ZARATHUSTRA

    Electric field and electric potential problem

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  21. oreo

    Electric potential and electric field

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  22. I

    Trying to understand Electric Potential

    I just watched a videos explaining electric potential and voltage in terms of gravitational potential. A negative charge was drawn with electric field lines converging into it and then a positive charge placed in the vicinity. The video explained that work was required to overcome the...
  23. PWiz

    Electric Potential formula derivation?

    Okay so I'm using Coloumb's law and the defining equation of electric field strength to find a proof (for my own satisfaction) for the electric potential formula: V_A = \frac{PE_A}{q}= \frac{Q}{4πε_0r} (where A is the position configuration of a point charge q in an electric field) My derivation...
  24. H

    Total electric potential energy of equilateral triangle

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  25. H

    Conceptual Question about electric potential

    Guys, i really need help on answering this question... Can a charged particle ever move from a low electric potential to a high electric potential and yet have its electric potential energy decrease? Explain. What i think is that, no it is not possible for a charged particle to move to a...
  26. S

    When does work equal negative electric potential energy

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  27. S

    Clarifying Power = +EPE/Time & Negative Current with Negative Charge

    if w = - change in epe why does power = +epe / time if power is supposed to equal w / t shouldn't it be equal to -EPE / time Please help me clarify this. epe= electric potential energy and also if current equals to Q/t is there a negative current if there is a negative charge? isn't current...
  28. S

    Zero Electric Potential Concept and Visualization

    Homework Statement Hi, I've been having problems visualizing and interpreting a situation where there is zero potential in a point, equidistant, between two opposite charges. What is the significance of this? Here's a sample problem:Consider two point charges. One has a charge of +1 μC and the...
  29. M

    Electric Potential Energy Question

    1. Homework Statement Two electrons start at rest with a separation of 5.0*10-12m. Once released, the electrons accelerate away from each other. Calculate the speed of each electron when they are a very large distance apart. Homework Equations ΔEK+ΔEE=0 The Attempt at a Solution Okay so I...
  30. E

    Electric Potential with Non-conducting sphere and conducting shell

    Homework Statement A spherical nonconductor of radius a carries charge +Q uniformly spread through its volume. 2 hemispherical conducting shells of inner radius b and outer radius c are placed concentrically with the nonconducting sphere to form a single conducting sphere. The conducting shell...
  31. S

    Calculate the electric potential inside the pipe

    Homework Statement A long pipe is split to four four pieces along its length. The quarters are slightly moved apart and attached to constant electric potentials ##U_0## and ##-U_0## as shown in the cross section of the pipe in the attached picture. The walls of the pipe are thin and the...
  32. D

    Electric potential ( with angle)

    Homework Statement The electric potential of a region of space is V= 200 / sq root (x^2 + y^2), where x and y are in meters. What are the strength and direction of the electric field at (x,y) = (2m,1m)? Homework EquationsThe Attempt at a Solution I took the negative derivative of V to find what...
  33. A

    Finding the Electric Potential

    Homework Statement 8 Charged drops of water each of radius 1 mm and having a charge of 10^(-10) Coloumbs are combined to form a bigger drop.Determine the potential of the bigger drop. Homework Equations Does the radius becomes 4*10^(-3)m,when it combines? Does the charge sum up to...
  34. M

    Electron move through capacitor

    Homework Statement An electron enters a region between two capacitor plates with equal and opposite charges. The plates are L=0.1 m by d=0.05 m, and the gap between the plates is h=0.002 m. During a short time interval of dt=0.002 s, while between the plates and far from the edges, the change...
  35. E

    Where Is the Electric Potential Minimum on a Circle in a Uniform Electric Field?

    The electric field at the origin is along the positive x axis. A small circle is drawn with the center at the origin cutting the axes at points A, B, C, and D having coordinates (a,0), (0,a), (-a,0), (0,-a), respectively. Out of the points on the periphery of the circle, the potential is minimum...
  36. C

    Electric Field due to Point Charges

    Homework Statement [/B] The following is on a practice exam I have been completing. In advance, it is part b I am struggling with. Two point charges Q1 = +5*10^(-6)C and -2*10^(-6)C are 50cm apart. a) Where along a line that passes through the two charges is the electric potential zero (apart...
  37. K

    Determining Electric Potential

    Homework Statement Consider a nonconducting sphere of radius r2. It has a concentric spherical cavity of r1. The material between r1 and r2 has a charge density p (C/m3). Take V=0 and r=infinity. Determine the electrical potential V as a function of the distance r from the center for (a) r>r2...
  38. C

    Electric Potential- Two Charges

    Homework Statement Two identical particles, each with a mass of 2.0 mg and a charge of 25 nC, are releasedsimultaneously from rest when the two are 4.0 cm apart. What is the speed of either particle at the instant when the two are separated by 10 cm? Homework Equations PE=ke*q1q2/r The...
  39. deedsy

    Electric potential linear charge

    Homework Statement A charge Q is uniformly distributed along a straight line of length a. Calculate V by integration, choosing the origin of the coordinates as the center of the charge. Next, expand this value of V up to terms in 1/r^2 Homework Equations V = \frac{\lambda}{4 \pi \epsilon_0 r}...
  40. C

    Calculating Chlorine Ion Acceleration & Speed of Light:Why?

    Question Assuming the electric potential difference between the inside and outside of a cell is 70 mV and the thickness of the region across which this exists is 7 nm, calculate the acceleration a chlorine ion would experience in the absence of other forces. In the absence of other forces how...
  41. P

    Find the potential difference in a rectangle

    Homework Statement [/B] Figure 20-3, referred to below, is 0.800m wide and 0.400m tall with "A" in the top left corner, "+4 microC" charge in the top right corner, "+2 microC" charge in the bottom left corner, and "B" in the bottom right corner. Two point charges of magnitude +4.00 μC and...
  42. Z

    Find the electric potential V(r)

    Hi, I have a homework of electromagnetism and I got stucked in a problem, can you help me, please? 1. Homework Statement Find the electric potential V(r) in the space produced by a density charge (rho) = (rho)0 e-(alpha) r In spanish: Enuentra el potencial V(r), en todo el espacio, producido...
  43. A

    Conductor with shell problem getting zero as answer?

    1. Problem Statement: The figure shows a cross-section view of a very long cylindrical cable. There is an outer tube made of copper, inner radius 2R, outer radius 4R. The inner copper wire has radius R and is concentric with the tube. The inner wire has charge density –2λ (per unit length)...
  44. W

    Electric Potential Energy concepts

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  45. Telemachus

    Electric Potential in Region z>0 Using Method of Images

    Hi there. The example to obtain the electric potential in the region z>0 by the method of images for a infinite grounded conducting plane, with a point charge q located at a distance d is a typical example of the application of the method of images. If we consider that the plane is located in...
  46. Joa Boaz

    The electric potential is defined by the function v(x,y,z) =

    My approach and solution, but not sure if it is correct path:
  47. C

    Electric Potential and Second Charge

    Homework Statement The electric potential at a position located a distance of 18.6 mm from a positive point charge of 7.50×10-9C and 10.9 mm from a second point charge is 1.02 kV. Calculate the value of the second charge. Homework Equations q2 = r2 * (v - (k * q1 / r1)) / k The...
  48. Adithyan

    Electric potential of a charged shell- Self potential?

    Homework Statement I recently encountered a problem wherein I was asked to calculate the potential difference between two non conducting concentric spherical shells of radii R1 and R2. Homework Equations ΔV=-∫E.dr The Attempt at a Solution While I was able to calculate the potentials of...
  49. 2

    Deriving the formula for electric potential?

    Homework Statement I'm getting really confused when it comes to electric potential. The definition I am using is 'the work done per unit charge on a small positive test charge when it is moved from infinity away to a point'. My first problem is that I'm not sure whether 'the work done' refers...
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