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.

View More On Wikipedia.org
  1. S

    Intuitive Definition of Electric Potential

    Hello all, For a few months, I've been (off and on) trying to come up with a more intuitive definition for Electric Potential (or Voltage, if you prefer), as all I can seem to find are mathematical equations. I believe I have finally come up with a satisfactory result, and I merely wanted to...
  2. popbatman

    Electric potential generated by an hemispherical charge distribution

    I need the electric potential generate by an hemuspherical constant charge density along the axis normal to the plane surface of the distribution an passing for the center of the hemisphere. In practice i have to solve the integral: ∫1/|x-x'| d^3x' over the volume occupied by the distribution...
  3. C

    Work and electric potential in a moving charge

    1. Explain briefly the relationship between electric potential and work in moving a positive charge q from point A to point B in an electric field Should I explain that work is potential energy plus kinetic energy? is it asking for that? and also, does the fact that it's a positive charge...
  4. T

    Electric potential at certain point from charged sphere

    Let's say I have a sheet of charge that is composed of a certain amount of charged atoms summing up to Q and a certain area A. The charge density would be Q/A = σ. I wish to find the elctrostatic potential from the sheet at point X. I believe that the electric potential should follow the...
  5. H

    Green's function representation of electric potential

    Hi, I have the following problem, I have an electric field (which no charge) which satisfies the usual Laplace equation: \frac{\partial^{2}V}{\partial x^{2}}+\frac{\partial^{2}V}{\partial y^{2}}+\frac{\partial^{2}V}{\partial z^{2}}=0 in the region \mathbb{R}^{2}\times [\eta ,\infty ]. So...
  6. R

    Electric potential vector or scalar sum?

    I'm having trouble fully understanding what electrical potential means. If there are two point charges of opposite signs and a point charge somewhere around them, we simply add the two voltages separately? Not as a vector sum? Also the concept of negative potential, does this mean that the...
  7. A

    Electric potential of a conducting rod in a homogen. electric field

    Hello, I have puzzled myself with a question: what is the potential of a conducting rod in a homogeneous electric field (net rod charge = 0)? To be more exact I imagine a conducting rod suspended on a non-conducting thread in the Earth electric field near and perpendicular to its surface. If...
  8. S

    Calculating Electric Potential in a Uniformly Charged Spherical Shell

    A non conducting spherical shell is uniformly charged. The electrostatic potential at the centre is 200v and the electrostatic potential at the distance r=50cm from the centre is 40v. Find the radius of sphere a. I am not sure where go with this. I know that the potential difference is...
  9. U

    Non uniform charge density and electric potential

    As shown in the figure, a rod of length 9.8 m lies along the x-axis, with its left end at the origin. The rod has a non-uniform linear charge density λ = αx, where α = 0.009 C/m2 and x is the position. Point A lies on the x-axis a distance 3.59 m to the left of the rod, as shown in the figure...
  10. V

    Electric Potential of 2 Point Charges

    Homework Statement The 2.1mm diameter spheres in the figure are released from rest. What are their speeds vc and vd at the instant they collide? Spheres: C has 2nC of charge and a mass of 1g. D has -1nC of charge and a mass of 2g. The starting distance between the two spheres is 10mm...
  11. P

    Electrostats, Electric potential question. Need a little direction.

    Homework Statement Two point charges 2q and 8q are placed at a distance r apart. Where should a third charge -q be placed between them so that the electrical potential energy of the system is minimum. a). at a distance r/3 from 2q b). at a distance 2r/3 from 2q c). at a distance r/16 from 2q...
  12. C

    Is Electric Potential Highest Between Two Positive Point Charges?

    Say you have two point charges, both are positive. Would I be correct in thinking that electric potential (V) would be highest at some point along the line between those two point charges, and then decrease as we get closer to each of the charges?
  13. S

    Electric Potential Energy with Three Postive Charges

    Homework Statement You have 3 charges, all +2.5 μC arranged on a field at positions (-3.0 cm, 0), (3.0 cm, 0), and (0, 3.0 cm). I have already calculated the stored electric potential energy to be 3.85 J. The question is: If the third charge (0, 3.0 cm) is released from rest, what is its change...
  14. E

    Electric potential distribution in a volume of varying conductivity

    Hey, Assume I have a very large tank of some liquid with uniform but medium conductivity. I now insert two fine wires into the tank some distance (D) apart, and create an electrical potential difference between them (V). 1) If I were to take my voltmeter (input impedance very high, so we...
  15. S

    Electric Potential Energy vs. Potential

    Hey all. I have a question regarding potential vs. potential energy. Basically, from what I can tell, the potential energy is a property of the system as a whole (it has a single value in any given situation) while the potential is a property of each specific point in space. Would this...
  16. W

    Electric potential at a distance r from a non-conducting sphere

    Homework Statement Determine the electric potential at a distance r from a non-conducting sphere of radius a and non-uniform charge density Br (where B is a constant) for each of the following cases: i. r>a ii. 0<r<a Homework Equations Electric field outside of the sphere...
  17. P

    Sign of scalar product in electric potential integral?

    the potential difference between b and a is defined as follows: V(b) - V(a) = -∫E \bulletdl the integral is taken from a to b. so the potential of a positive charge, with infinity as reference, is V(r) - V(infinity) = V(r) = -∫E \bulletdl the integral is from infinity to r...
  18. 5

    Electric potential of concentric spheres

    Homework Statement attached image http://sphotos.xx.fbcdn.net/hphotos-snc7/148934_353406858048194_100001366491698_897020_688558166_n.jpg Homework Equations V = integral of E * dr The Attempt at a Solution I do not completely understand the solution to part B. I was able to solve it...
  19. S

    Electric Potential at Point D in a Rectangle with Three Charges

    Homework Statement The diagram shows three charges, A (+5.0 μC),B (-7.0 μC), and C (+2.0 μC), placed at three corners of a rectangle. Point D is the fourth corner. What is the electric potential at point D? Homework Equations VEL = \frac{(k)(q1)}{d}The Attempt at a Solution I don't know how...
  20. Z

    How can electric potential contain so much information?

    Question is pretty simple and arose when doing one of the usual integrals to find the electric field. This one concerned the field above the middle of a uniform line distribution of charge. If you wish to calculate the field you must take in mind that the horizontal components cancel. However if...
  21. F

    Electric potential and earth/ground

    I was just wondering if the following is true/possible: - Could a circuit be made that is connected from a terminal on one battery, through a load, and then connected to the opposite terminal of another battery, where the batteries aren't touching? I believe it isn't possible, but would...
  22. H

    How Electric potential and potential difference work in batteries

    How is electric potential manipulated in batteries? Why do some batteries have a rating of 1.5v and others have ratings of 1.25v? I'm not looking for the answer of "its the materials used in the chemical reaction" because I know that.WHAT DO THESE MATERIALS DO DIFFERENTLY TO THE PHYSICS OF THE...
  23. N

    Find the Electric Field if Electric Potential is given at two PointsHelp needed

    Homework Statement Given that on the x-axis on at -1 the V is 120V at the point +1 V is 80 V . What is the Electric field at the origin (0,0) OPTIONS a)must be equal to 20 b)may be equal to 20 c)may be greater than 20 d)may be less than 20 Homework Equations The Attempt at a...
  24. T

    Electric Potential Energy defintiion

    I've Had this doubt from a long time back : Being in high school my physics teach simply stated that No explanations given. To quench my thirst I went through books and things . I found one difinitive result : a: In this Video http://bit.ly/wl8-0204 Prof.Walter Lewin Says...
  25. T

    Ranking Electric Potential Energies: A=C>B=D

    Rank the electric potential energies of the systems of charges shown in the figure below from largest to smallest. Indicate equalities if appropriate. (Use only ">" or "=" symbols. Do not include any parentheses around the letters or symbols.) I was thinking A=C>B=D Please help me if I am wrong!
  26. F

    Electric Potential: Neg. Charge, Positive, Mid Point?

    is the electric potential arround an isolated negetive charge considered negetive or positive? Also, at the mid point between a negetive and a positive charge of same charge, is the electric potential zero or not?
  27. T

    Electric Potential of a Cylinder using Poisson's Equation

    Homework Statement Consider a homogeneously charged, infinitely long, straight wire of finite radius R. Determine the potential \phi(r) of the wire for r ≤ R and for r ≥ R. You must use the Poisson-Equation! Homework Equations Δφ(r) = -ρ(r)/ε ⇔ \frac{1}{r}\frac{∂}{∂r}(r\frac{∂φ}{∂r}) +...
  28. S

    Electric potential energy of the two protons?

    Homework Statement The nucleus of a helium atom contains two protons. In a simple model of this nucleus, the protons are viewed as point particles separated by a distance of 1.0 fm (1.0 x 10^-15 m). What is the electric potential energy of the two protons? please do step by step.
  29. I

    Electric Potential, Capacitance and charge of a Geiger Counter

    Homework Statement Find the potential difference, capacitance of the Geiger Counter and the charge on the anode. So, we have a Geiger Counter with low-pressurized neon inside. What we want is to have an alpha particle or electron to travel into the Geiger Counter with enough energy to collide...
  30. E

    Electric Potential of three concentric spheres

    Hey, i have a conceptual doubt. Suppose there are three concentric conducting spheres A,B,C having radius a,b,c (a<b<c). We put charge q1, q2 and q3 on these three surfaces A,B,C respectively. Now using gauss law, we can prove that Charge on inner surface of A is 0 Charge on...
  31. F

    Electric Potential, conducting sphere in a conducting shell

    Homework Statement The electric potential at the center of a (5.00cm radius) metallic sphere is zero Volts. The sphere is surrounded by a concentric conducting shell of 10.0cm outer radius and a thickness of 2.0cm. The shell has a net charge of +20mC. a.)Find the charge on the sphere. b.)Give...
  32. E

    Finding out if work is done with between two points with same electric potential

    if two points have the same electric potential, is it true that no work is required to move a test charge from one point to the other? Does that mean that no force is required, as well?
  33. lonewolf219

    Electric Potential(V) and Electric Potential Energy(U) laws

    Hi, I was wondering if anyone could tell me if these 4 following statements are correct? 1. V increases as a particle nears a proton 2. V decreases as a particle nears an electron 3. U increases as a particle moves in opposite direction of Electric Field 4. U decreases as a...
  34. I

    What is the electric potential derivative when x=2 and y=1?

    Homework Statement The electrical potential can be described by the following equation: V= 200/(x2 + y2 )1/2 find dV when x=2 and y=1 Homework Equations n/a The Attempt at a Solution dv/d(x,y) = ∂/∂x + ∂/∂y =200/(x2 + y2)(1/2) +200/(x2 + y2)(1/2) replace variables with C where...
  35. Biosyn

    Electric Potential and charge problem

    Homework Statement A charge of +9q is fixed to one corner of a square, while a charge of -8q is fixed to the opposite corner. Expressed in terms of q, what charge should be fixed to the center of the square, so the potential is zero at each of the two empty corners? Homework Equations V =...
  36. K

    Electric field strength and electric potential in a sphere

    Given a solid metal sphere where all the positive charges are distributed evenly on the surface of the metal sphere. My textbook says that there is no electric field strength in the middle of the metal sphere because the charge = 0. However, my understanding is that wouldn't the center of the...
  37. P

    Electric potential from electric field at 2 points

    Homework Statement i have a sphere with center at origin that is partially empty inside with a non-uniform charge. i have 2 arbitrary points outside the sphere. find the difference in potential between the 2 points.Homework Equations The Attempt at a Solution 1) find total charge of sphere 2)...
  38. D

    Electric potential between two point charges

    Homework Statement Two point charges are separated by a distance r. If the separation is reduced by a factor of 3/2, by what factor does the electric potential between them change? A. 3/2 B. 2/3 C. 9/4 D. 4/9 E. Sqrt(3/2) Homework Equations The Attempt at a Solution Honestly I...
  39. G

    Cylindrical shell- electric potential problem

    A very long insulating cylindrical shell of radius 6.40 cm carries charge of linear density 8.90μC/m spread uniformly over its outer surface. What would a voltmeter read if it were connected between the surface of the cylinder and a point 4.00 cmabove the surface? λ=dq/dr V=k∫dq/r...
  40. F

    Electric Potential of a hollow cylinder

    Homework Statement A hollow cylinder of radius r and height h has a total charge q uniformly distributed over its surface. The axis of the cylinder coincides with the z axis, and the cylinder is centered at the origin, as shown in the figure. What is the electric potential V at the...
  41. C

    Abs Values in Electric Potential & Potential Difference?

    I'm a little bothered with the inconsistency in notation of electric potential (V) and potential difference (ΔV) because they're apparently used synonymously... but what really confuses me more is that I've seen absolute value around ΔV sometimes. It may not matter (theoretically or...
  42. T

    Electric Potential of grounded hollow metal sphere

    Homework Statement There is a solid metal ball of radius 'a' (with charge Q) that is placed inside a hollow metal sphere (inner radius = 'b', outer radius = 'c'). The metal sphere is grounded (so V = 0 at r = c). a) Find the electric potential V everywhere. b) Find the charge on the metal...
  43. S

    What is the electric potential midway between the two charges?

    Homework Statement Consider two equal positive charges (q=+2.0 µC) a distance of 3.0 cm apart. What is the electric potential midway between the two charges? What is the E field at this point? I got the work and everything all solved out, i just don't know where some of the numbers came...
  44. P

    Electric potential equals the negative area under the graph

    When taking about potential and electric field, potential difference is equal to the negative of the area under the graph of E vs distance? why is that. My book defines it as the negative integral of Force times ds or V(intitial) - area under the curve. I don't understand why it's negative. I...
  45. A

    Electric potential question (check my work)

    Homework Statement A beam of electrons with energy 1.20 keV (per electron) is directed towards a solid copper sphere of radius 1.25cm. a) Determine the velocity of the electrons in the beam. b) The beam continues to send electrons into the sphere until it is charged up enough to repel the...
  46. M

    At what point on the x-axis is the Electric Potential zero?

    Homework Statement A 13.0nC charge is at x = 0cm and a -1.1nC charge is at 6cm. At what point or points on the x-axis is the electric potential zero? Let X0 be a position on the x-axis Let V1 be the electrical potential at a point due to the 13nC charge Let V2 be the electrical potential...
  47. A

    Electric Potential Energy Question

    Homework Statement A uranium nucleus in a reactor captures a slow neutron and divides, or fissions, into two smaller daughter nuclei. Assuming the nucleus divides into two equal daughters with charge Q=46e and diameter d=2x10-14m, calculate their electric potential energy. Homework...
  48. lonewolf219

    Why electric potential of arc treated like point charge

    Homework Statement Give an expression to find V of Arc of uniform charge (at the center, or origin) Homework Equations V=kQ/R The Attempt at a Solution the solution is kQ/R. I'm wondering why an arc can be treated like a point charge... Is this reason partly connected to a...
  49. J

    Help with two quick electric potential and voltage problesm

    Homework Statement 1) How much work is needed (done by the field) to move a -6.0 µC charge from ground to a point whose potential is +7.00 V higher? 2)An electron starts from rest 74.5 cm from a fixed point charge with Q = -0.150 µC. How fast will the electron be moving when it is very far...
  50. J

    Electric potential energy finding velocities

    Two metal balls of mass m1=3.41g (diameter=3.41mm) and m2=7.88g (diameter=7.88mm) have positive charges of q1=1.41nC and q2=9.19nC. A force holds them in place so that their centers are separated by 8.79mm. What will their velocities be after the force is removed and they are separated by a...
Back
Top