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. B

    Electric Potential and Electric fields

    Homework Statement Can there be a point in space where there is an electric potential but not electric field? Can there be a point in space where there is an electric field but no electric potential? Explain you answer. What would the electric field lines look like if the electric field was...
  2. Marcus Nielsen

    Electric potential due to a solid sphere

    Hello Guys! This is my first post so bear with me. I am currently studying the basics of electrostatics using the textbook "Introduction to electrodynamics 3 edt. - David J. Griffiths". My problem comes when i try to solve problem 2.21. Find the potential V inside and outside a uniformly...
  3. T

    How electric potential boundary condition works

    Homework Statement [/B] Inside a sperical dielectric mass there is a electric dipole on the center of the sphere. The sphere has radius a. This dieletric sphere is inside and on the center of a conductive spherical shell of radius b. The problem asks to find the potentials and then the...
  4. bachir1994

    The physical meaning of electric potential

    I read that : An electric potential (also called the electric field potential or the electrostatic potential) is the amount of work needed to move a unit positive charge from a reference point to a specific point inside the field without producing any acceleration. Typically, the reference point...
  5. D

    Electric potential related to electric field question

    Homework Statement (i) Consider a non-conducting sphere of radius R with non-homogeneous charge density ρ = ρ(r) = r, where r is the radial co-ordinate. (a) Find the electric field inside and outside of the sphere(b) Find and plot the electric potential inside and outside of the sphere...
  6. AdrianMachin

    Electric potential between two concentric spherical shells

    Homework Statement (The complete problem statement and solution are inside the attached picture) Two isolated, concentric, conducting spherical shells have radii ##R_1=0.500 m## and ##R_2=1.00 m##, uniform charges ##q_1=2.00 mC## and ##q_2=1.00 mC##, and negligible thicknesses. What is the...
  7. an_single_egg

    Determining Electric Potential with Charge Density

    Homework Statement A nonconducting sphere of radius r0 carries a total charge Q. The charge density ρE increases as the square of the distance from the center of the sphere, and ρE=0 at the center. a) Determine the electric potential as a function of the distance r from the center of the...
  8. AdrianMachin

    Plot 3D graph of electric potential of a charged particle

    Homework Statement Plot the electric potential ##V(r)## due to a positively charged particle located at the origin of an XY plane. Homework Equations ##V=\frac 1 {4πε_0} \frac q r## The Attempt at a Solution I'm unfamiliar with 3D coordinates at this time, but I like to know how can I plot it...
  9. esha

    Why is electric potential present inside a conductor?

    potential energy is the work done by an external force in taking a body from a point to another against a force. on the surface of a conductor the electrostatic charges arrange themselves in such a way that the net electric field is always zero. so if there isn't any force to act against why...
  10. AdrianMachin

    Calculating work on an electron on an equipotential surface

    This is not a homework, but a question formed in my mind after reading my textbook. Homework Statement Consider an electron (a charged particle) on a metallic equipotential surface. We know that all the points on the surface are equipotential, thus there will be no force on charged particles...
  11. N

    Calculating electric potential with a uniform elect field

    Homework Statement In a certain region of space, there is a uniform electric field of magnitude 25.0 V m^-1 directed at 30.0 degrees to the direction of the positive x-axis and at 60.0 degrees to the direction of the positive y-axis. (There is no z component of the electric field.) The electric...
  12. AdrianMachin

    A problem regarding the electric potential of an electron

    Homework Statement There is a sample problem in my physics textbook (Fundamentals of Physics, 10th Edition by David Halliday and others) which has some confusion in it for me. Please take a look at the snapshot I took, in the attachments. Homework Equations 3. The Attempt at a Solution [/B]...
  13. F

    Electric potential of charged concentric spheres

    Homework Statement Two conducting concentric spheres of negligible thickness. The radii of the spheres are R_1 and R_2, respectively, with R_2>R_1. A charge q_2 is placed on the external sphere. A charge q_1 is placed on the internal sphere. Assume that the electric potential is zero...
  14. gfd43tg

    Standard Electric Potential of a razor blade for shaving

    Hello, I was wondering if anyone knows what the Standard electric potential of a razor blade might be? I read from a website this is a composition of a razor blade, I think they all have somewhat similar compositions, notably the presence of chromium. From...
  15. David23454

    Find electric potential due to charge distribution

    Homework Statement In a certain region, the electric potential due to a charge distribution is given by the equation V (x, y, z) = (3x2y2+yz3-2z3x)V0/a4 where a, x, y, and z are measured in meters and V and V0 are in volts. What is the magnitude of the electric field at the position (x, y, z)...
  16. H

    What is the Mistake in My Electric Potential Problem Calculation?

    I am having trouble understanding this problem in Electric Potential. (Source: OpenStax, Chapter 19) Now consider another system of two point charges. One has a mass of 1000 kg and a charge of 50.0 µC, and is initially stationary. The other has a mass of 1.00 kg, a charge of 10.0 µC, and is...
  17. Haynes Kwon

    Electrical Potential Energy and Electric Potential

    Hi. Getting straight to the point, what is the difference between electrical potential energy and electric potential? Please be as specific as you can. Thank you.
  18. Nabin kalauni

    Is electric field always 0 if potential at a point is 0?

    I understand that if electric field at any point is 0, it implies that potential is constant not necessarily 0. But what if the potential at a point is 0? Does it imply that electric field is 0? Me and my friend had an argument and I am in the favour of electric field not being 0. Do I win guys...
  19. J

    Deriving expression for potential of a point charge

    Homework Statement I am trying to derive an expression for the potential of a positive point charge by bringing in another positive test charge in from infinity to a point at a distance R from the point charge. Homework Equations $$V_f - V_i = - \int \vec E \cdot d \vec r \, dr$$ The Attempt...
  20. B

    Electric Potential Problem: Using the Method of Images

    Homework Statement Homework Equations The Attempt at a Solution I have no idea what it looks like and how to approach this. Is this right description?
  21. E

    Finding electric potential between two concentric spheres.

    Homework Statement A spherical shell with inner radius A and outer radius 3A which has a uniform charge density, i.e charge per unit volume, p0. Find difference in electric potential between the center of the shell and a point a distance 2A from the center. Homework Equations The answer given...
  22. D

    Electric potential of a conical surface

    Homework Statement (From Griffiths problem 2.26) : A conical surface (an empty ice-cream cone) carries a uniform surface charge σ. The height of the cone is h, and the radius of the top is R. Find the potential difference between points a (the vertex) and b (the center of the top).Homework...
  23. S

    Electric Potential vs Electric Field?

    I've read that in an electric field due to it being a vector if its mirrored symmetrically the components cancel out. However, the electric potential is a scalar so the components are added not canceled out. This is consistent with one question in my physics H.W., but not for another question...
  24. V

    Find electric potential of field inside and outside nucleus

    Homework Statement Derive following expression for the electrostatic potential energy of an electron in the field of a finite nucleus of charge, ##+Ze##, and radius, ##R=r_0A^{1/3}##, where ##r_0## is a constant. (Charge density is constant.) The potential we are asked to derive is: $$ V(r) =...
  25. lz975545

    Electric potential at the bottom of a ring?

    Homework Statement [/B] A circular ring of radius "a" has a total charge Q uniformly distributed along the top half. (Q is distributed along the semicircle in quadrants I and II). What is the potential at a point located on the bottom of the ring (observation point is on the ring in quadrant...
  26. P

    Finding an expression for Electric Potential?

    Homework Statement There is a thin rod with charge Q that has been bent into a semicircle with radius R. Find an expression for the electric potential at the center. Radius = R Charge = QHomework Equations V = ∫(k * dq)/rThe Attempt at a Solution dq = λdx λ = Q/L L = pi * r V = kQ / LR ∫ dx =...
  27. C

    Finding electric potential where electric field is zero

    Homework Statement A -10.0 nC point charge and a +20.0 nC point charge are 15.0 cm apart on the x-axis. What is the electric potential at the point on the x-axis where the electric field is zero? Homework Equations ##E = k\frac{Q}{r^2}## ##V = k\frac{Q}{r}## The Attempt at a Solution I've set...
  28. D

    Calculating the Potential Energy of a 3-point charge config.

    Homework Statement Charge q1= 8.5 nC is located at the coordinate system origin (0,0), while charge q2= -4.46 nC is located at (a,0), where a= 1.5 m. The point P has coordinates (a,b), where b=0.95 m. A third charge q3= 16.5 nC will b added later. It is a 3 part question, first asking for the...
  29. jlmccart03

    How to find electric potential given only velocity

    Homework Statement Given v = v=4.8×105m/s find the change in electric potential. Homework Equations ΔV = Vf-Vi = -W/q The Attempt at a Solution I really don't know any other formula that has the use of velocity to find ΔV. So how does velocity end up into the mix in finding ΔV?
  30. jlmccart03

    Magnitude of the work done by electric field.

    Homework Statement The membrane around a cell normally has layers of charge that create a potential difference between its outer and inner surfaces. This difference is about 72 mV . When a singly ionized potassium ion moves through a channel in the membrane passing from the outside to the...
  31. jlmccart03

    Electric Potential Difference

    Homework Statement Two charged rods, each with net charge -Q0 are held in place as shown in the top view diagram below. a. A small test charge -q0 travels from point X to point Y along the circular arc shown. i. Draw an arrow on the diagram at each point to show the direction of the electric...
  32. S

    Find change in electric potential energy

    Homework Statement A uniform electric field of magnitude 4.1 ✕ 10^5 N/C points in the positive x-direction. Find the change in electric potential energy of a +5.3 µC charge as it moves from the origin to each of the points given below. (a) (0, 6.9 m) __ J (b) (6.9 m, 0) __J (c) (6.9 m...
  33. Iftekhar Uddin

    2 Questions: How Electric Potential affects a charge

    1. There's a picture of Electric Field lines going down. Now between these electric field lines (affected by them) are points A and B at differing heights and positions. My question is, how does potential change as you go up/down and left/right? I would like to think that going down means you're...
  34. Iftekhar Uddin

    I Probably a Dumb Question: How are E and (delta)V correlated?

    What I Think I Understand: ΔV = Ed (d being dstance) and that V = kq/r please correct me if I'm misunderstanding those. What I need to know: When E = 0, what happens to the electric potential? and vice versa. Me Working it out: So if i use the first equation up here, If E = 0, then electric...
  35. fuvest

    Electrical Circuit Problem / Electric Potential Difference

    Homework Statement In the following picture, the absolute value of the difference in electric potential, between points A and B is: A)5V B)4V C)3V D)1V E)0V Homework Equations E =qV V = iRThe Attempt at a Solution I have no idea where to start on this one, just started my electric circuits...
  36. F

    Electric Potential reference value (or zero).

    Hello forum members, The electric potential for a point charge is a scalar function given by $$V = \frac {kq}{r}$$ This means that the potential has a nonzero value everywhere. The potential becomes ##V=0## when ##r=\infty##. However we know that what matters is the potential difference...
  37. lightofthemoon

    Electric Potential at Center of Sphere

    Homework Statement A solid conducting sphere of radius R and carrying charge +q is embedded in an electrically neutral nonconducting spherical shell of inner radius R and outer radius 9 R . The material of which the shell is made has a dielectric constant of 2.0. Relative to a potential of zero...
  38. Cocoleia

    Dipole moment, electric potential

    Homework Statement I am given this picture and I know that |q1|=2nC, |q2|=5nC, d=1mm I need to first find the total dipole moment of the system. Then I need to find an equation that represents the electric potential due to this net dipole moment for all (everywhere) Homework Equations p=qd...
  39. lightofthemoon

    Electrostatic Potential / Work Question?

    Homework Statement An electron and a proton are held on an x axis, with the electron at x = + 1.000 m and the proton at x = - 1.000 m. If a second electron is initially at 20 m on the x axis, and given an initial velocity of 350 m/s towards the origin, it does not reach it. How close to the...
  40. RoboNerd

    Question about work on an electric charge

    Homework Statement If the electric field does positive work on a negative charge as the charge undergoes a displacement from point A to point B within an electric field, then the electric potential energy is a) negative b) positive c) increases d) decreases e) electric fields can not do work...
  41. M

    -- E/M conceptual question regarding electric potential

    So in a graph where V is a function of x, when the slope is negative what does that mean about the direction of the field along the x axis? What about when the slope is positive?
  42. Schaus

    Electric potential at a point due to two charges

    Homework Statement What is the electric potential at P due to charges Q1 and Q2...
  43. K

    Grounded conductor and Electric field potential question ?

    Homework Statement [/B]Homework Equations V= kq/r.[/B]The Attempt at a Solution For 8-8, I do not really know how to approach it. For 8-14 , I think that q2=-q1 and q3=q1+q2. I can now use V=kq/r and then find the equations for r>R3 , r=R3 , R2<r<R3 , r=R2 and R1<r<R2 and then graph...
  44. C

    Electric potential of a ring

    Homework Statement A ring of radius a is made from a charge wire with a uniform charge density λ. a) Calculate the electric potential due to the ring as a function of distance from its center along the axis of the ring passing through the center, perpendicular to its plane b) If a particle...
  45. NihalRi

    Two point charges and electric potential difference

    Homework Statement In an experiment modeling point charges I had to find equipotential lines. I did so using a voltmeter. The results looked like this: Not a good quality picture, but the equipotential line on the right says 1.3 mV and the one on the left says 2.3mV. From this I had to...
  46. PhanicKnight

    Diagram of electric potential difference in plate capacitor

    Homework Statement Plate capacitor is filled with two dielectrics of constants 3 and 4, and with a metal as seen in the picture. If the el. field in the first dielectric is 30 kV/cm, do: a) diagram of el. potential difference with calculated characteristic values using point C as a...
  47. doktorwho

    Calculate the electric potential of a sphere

    Homework Statement A metal sphere of radius ##a=1cm## is charged with ##Q_a=1nC##. Around a sphere is placed a spherical shell of inner radius ##b=2cm## and outer radius ##c=3cm##. The electrical potential of the shell in refenrence to a point in the infinity is ##V=150V##. The spheres are in...
  48. L

    Electric potential. In circuits. + -

    Electric potential energy in circuits. Here is what I know: The electric potential between two points is the work done against electric forces to move that mass of charge between those two points. What does this mean in a circuit? I know basic things about electric field, the test charge...
  49. T

    Electric potential just after switch is opened.

    Homework Statement [/B] https://postimg.org/image/6dbwajk91/ (Image inserted by moderator to make it visible in-post) In the circuit the switch is closed for several seconds, then opened. Make a graph with the abscissa time in milliseconds, showing the potential of point A with respect to...
  50. NiendorfPhysics

    Radius of Half Electric Potential Energy

    Homework Statement There is a solid cylinder of radius a and then empty space then a shell cylinder of radius b. Show that half of the stored potential energy lies within a cylinder of radius $$\sqrt{ab}$$ Homework Equations In the attempt The Attempt at a Solution I'm not sure what they...
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