What is equipotential: Definition and 110 Discussions

In mathematics and physics, an equipotential or isopotential refers to a region in space where every point is at the same potential. This usually refers to a scalar potential (in that case it is a level set of the potential), although it can also be applied to vector potentials. An equipotential of a scalar potential function in n-dimensional space is typically an (n − 1)-dimensional space. The del operator illustrates the relationship between a vector field and its associated scalar potential field. An equipotential region might be referred as being 'of equipotential' or simply be called 'an equipotential'.
An equipotential region of a scalar potential in three-dimensional space is often an equipotential surface (or potential isosurface), but it can also be a three-dimensional mathematical solid in space. The gradient of the scalar potential (and hence also its opposite, as in the case of a vector field with an associated potential field) is everywhere perpendicular to the equipotential surface, and zero inside a three-dimensional equipotential region.
Electrical conductors offer an intuitive example. If a and b are any two points within or at the surface of a given conductor, and given there is no flow of charge being exchanged between the two points, then the potential difference is zero between the two points. Thus, an equipotential would contain both points a and b as they have the same potential. Extending this definition, an isopotential is the locus of all points that are of the same potential.
Gravity is perpendicular to the equipotential surfaces of the gravity potential, and in electrostatics and steady electric currents, the electric field (and hence the current, if any) is perpendicular to the equipotential surfaces of the electric potential (voltage).
In gravity, a hollow sphere has a three-dimensional equipotential region inside, with no gravity from the sphere (see shell theorem). In electrostatics, a conductor is a three-dimensional equipotential region. In the case of a hollow conductor (Faraday cage), the equipotential region includes the space inside.
A ball will not be accelerated left or right by the force of gravity if it is resting on a flat, horizontal surface, because it is an equipotential surface.
For the gravity of Earth, the corresponding geopotential isosurface (the equigeopotential) that best fits mean sea level is called the geoid.

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  1. P

    Is Va > Vb if Vb - Va = -6000V?

    if Vb-Va=-6000V, that means Va has to be bigger than Vb right?
  2. I

    Equipotential surfaces; finding the radius

    Homework Statement a metal sphere of radius 0.39 m carries a charge 0.55 μC. Equipotential surfaces are to be drawn for 100-V intervals outside of the sphere. Determine the radius of the first, tenth and 100th equipotential from the surface. Homework Equations V = kQ / r Volt =...
  3. A

    Calculating Work and E-field from and equipotential contour graph

    Homework Statement A) Calculate the work performed by an external agent to move a charge of -0.59x10-12 C from `i' to `b'. B) Calculate the magnitude of the electric field at `k' Homework Equations W = q∆V Where ∆V is the potential difference between the two potential lines...
  4. Pengwuino

    Calculating equipotential surfaces

    So this may be a bit silly, but one thing I've never really learned in all my years is how one actually goes about calculating equipotential surfaces for arbitrary potentials? Let's say I have a potential that goes like \Phi = A_0e^{-\left({{r}\over{r_0}}\right)^2}\cos^2 (\phi) \sin^2(\theta)...
  5. B

    Show the equipotential surface is a spherical surface

    Homework Statement consider now a system of two charges: a point charge q>0 located at the position (x,y,z)=(a,0,0) and a point charge -q/2 located at (-a,0,0).Show that the equipotential surface V=0, i.e. with the same potential than at infinity, is a spherical surface. Determine the centre...
  6. S

    Equipotential Surface: Kinetic Energy & Variability

    What is the kinetic energy of particle moving in a equipotential surface? Whether is it constant or variable?
  7. W

    What Is the Shape of Equipotential Surfaces Near a Charged Disk?

    Homework Statement Find the equipotential surface at the edge of a uniform electric charged disk ? Homework Equations \nabla^2 V= - \displaystyle \frac{\rho}{\epsilon} \displaystyle V= \iiint_R \frac{ {\rho}r dr d\phi dz}{4 {\pi} {\epsilon}|\vec r -\vec r'|} The Attempt at a...
  8. T

    Drawing equipotential lines and field lines

    Homework Statement Draw the electric field lines and equipotential lines for the electrode configure. Assume one of the parallel plate is at a positive potential and the other one is grounded. Homework Equations The Attempt at a Solution I know the electric field lines and...
  9. J

    Electric Field Lines and Equipotential Contours

    Homework Statement The adjacent figure shows the E-field lines (with arrows) and equipotential contours for a certain charge configuration. Determine for each of the following statements whether it is true or false. Assuming that these contours are those of a point charge at the origin...
  10. M

    Equipotential surfaces for the given charge distribution

    Homework Statement Two infinitely long wires running parallel to the x-axis carry uniform charge densities \lambda and - \lambda. a.) Find the potential at any point (x, y, z) using the origin as your reference. b.) Show the equipotential surfaces are circular cylinders, and locate the...
  11. G

    Equipotential lines for two charges

    Hi there, Could you describe for me what happens to the equipotential lines of two charges as they move close to each other. Thanks
  12. T

    Flux and Equipotential Lines of a Harmonic Equation

    Homework Statement I'm not a physics person at all, but I need to solve this Electrostatics problem and I'm stuck. Homework Equations V(x,y)=(2/pi)arctan(\frac{-2iy}{1-x^2-y^2}) The Attempt at a Solution I've derived this equation from a given set of parameters, V(x,y)=1 when...
  13. L

    Are Conductors Truly Equipotential?

    Homework Statement in my exam, i had the following question say true or false--conductors are equipotential. what is the answer? Homework Equations The Attempt at a Solution
  14. H

    Equipotential Lines Homework: Calculating Electric Field Strength

    Homework Statement The figure below shows the equipotential lines for a uniformly varying electric field. [PLAIN]https://wug-s.physics.uiuc.edu/cgi/courses/shell/common/showme.pl?cc/DuPage/Phys1202/fall/homework/Ch-20-Potential/equipotential_lines/equ-lines-1.jpg A) What is the...
  15. N

    Why is the surface of a conductor equipotential?

    I am having trouble understanding this. For example, say I have this: [positive point charge] [A][neutral conducting sphere][B] [...infinity] I know the point charge will create a field radially outward. But now I'm thinking of a test charge being brought in...
  16. P

    Equipotential Surfaces for Different Charge Configurations

    Homework Statement Sketch the equipotential surfaces which result from the following charge configurations: (a) a point charge (b) a spherically symmetric charge distribution (c) a very large, plane, uniformly-charged sheet (d) a long, uniformly-charged cylinder (e) an electric dipole...
  17. P

    Equipotential Surfaces for Different Charge Configurations: Where to Find Them?

    Homework Statement Sketch the equipotential surfaces which result from the following charge configurations: (a) a point charge (b) a spherically symmetric charge distribution (c) a very large, plane, uniformly-charged sheet (d) a long, uniformly-charged cylinder (e) an electric dipole...
  18. P

    Equipotential surfaces - - Pictures

    Homework Statement Sketch the equipotential surfaces which result from the following charge configurations: (a) a point charge (b) a spherically symmetric charge distribution (c) a very large, plane, uniformly-charged sheet (d) a long, uniformly-charged cylinder (e) an electric dipole...
  19. I

    Equipotential Surfaces and Electric Field

    Homework Statement A given system has the equipotential surfaces shown in the figure . http://session.masteringphysics.com/problemAsset/1122530/1/Walker.20.39.jpg A)What is the magnitude of the electric field? B)What is the direction of the electric field? (in degrees from the +x...
  20. L

    Understanding Equipotential Lines and Electric Field Lines

    I understand the concept of electric field lines but don't understand the interaction with the equipotential lines. I understand that along each equipotential line/surface that there is no change in potential energy. I also understand the field lines need to cross perpendicularly with the...
  21. N

    Work done by external forces on an equipotential surface.

    The question I am having trouble with shows an image of 2 different conductors, one is at +300 volts, while the other is -600 volts with a few lines going in between which circle around. The points on the equipotential surface are on lines labeled as a (which lies on a -200V line) and the other...
  22. W

    Equipotential surfaces electric field problem

    Homework Statement A given system has the equipotential surfaces shown in the figure What is the magnitude of the electric field? What is the direction of the electric field? (degrees from + x axis What is the shortest distance one can move to undergo a change in potential of 5.00...
  23. M

    Equipotential Lines in a Uniform Electric Field: Force & Distance

    In a uniform electric field, where 2 plates are placed horizontally and are parallel, the electric field is vertical.. What about the equipotential lines? Are they horizontal?Also, I need to draw a graph of how the Force on an electron varies with the distance from the bottom plate, and this is...
  24. N

    What is the charge ratio between two equipotential spheres?

    Homework Statement A spherical potential conductor of radius R1 is charged to 20kV. When it is connected by a long, fine wire to a second sphere faraway. its potential drops to 12kV. What is the radius of the second sphere. Homework Equations V=kq/r The Attempt at a Solution So...
  25. K

    Calculation of electric field from a set of equipotential surfaces

    Homework Statement A set of concentric hemispherical surfaces is given, each of which is an equipotential surface. These concentric surfaces do not, however, have the same value of potential, and the potential difference between any two surfaces is also not constant. The surfaces are spaced...
  26. L

    Equipotential lines in an experiment setup

    Homework Statement The problem has two thin metal bar electrodes, one setup to be positive and one setup to be negative. A metal circular disc is placed between the two bars. Why do the equipotential lines near the edge of the bar run parallel to the bar? The setup looks kind of like this...
  27. L

    Equipotential Lines and Electric Fields Labratory Experiment

    Homework Statement Our lab is not online, but this is so similar to what we did. http://physics.fullerton.edu/~SAM/PDF/Lab%20Manuals/212/Individual%20Experiments/Equipotential%20Surfaces%20E6.pdf" Instead of the ten that they set their voltage to, we set ours to 12. Homework Equations...
  28. K

    Equipotential Surfaces: Understanding & Conceptual Problems

    I need help with developing a good understanding of equipotential surfaces corresponding to regions of three dimensional electric fields. I would appreciate if someone could refer me to a site or sites where this is comprehensively explained along with illustrations and with related conceptual...
  29. J

    What determines the shape and spacing of equipotential lines?

    Homework Statement What determines the shape and spacing of equipotential lines?Homework Equations NoneThe Attempt at a Solution I think the fact that equipotential lines have to be perpendicular to the surface determine the shape of the lines. I'm not sure what determines the spacing. Is it...
  30. W

    Magnetic monopoles, electric field lines and equipotential surfaces

    Homework Statement (i) Explain why it would not be possible to write the magnetic Field (B-field) in terms of a vector potential (A) IF magnetic monopoles existed. (ii) For an electrostatic field (E-field), define the electrostatic potential (Fi), and explain CONCISELY what is meant by a...
  31. T

    How Do Equipotential Contours Indicate Charge and Field Strength?

    Homework Statement The lines show equipotential contours in the plane of three point charges, Q1, Q2, and Q3. The positions of the charges are marked by dots. The values of the potentials are in kilovolts as indicated, e.g., +5 kV, −5 kV; the contour interval is 1 kV. The letters denote...
  32. J

    Drawing Electric Field Lines and Equipotential Lines

    Homework Statement You have two metal electrodes, not touching each other. One is a circle and one is like a thin plank. The plank is at a lower electric potential. Draw electric field lines between them, including direction. Draw equipotential lines in the space between the electrodes...
  33. G

    I'm having trouble visualizing the orientation of the equipotential surfaces.

    Homework Statement Consider a region in space where a uniform electric field 6700 N/C points in the negative x direction. What is the orientation of the equipotential surfaces? a.Parallel to the xz-plane. b.Parallel to the yz-plane. c.Parallel to the xy-plane. Homework Equations...
  34. C

    Solve Equipotential Lines: Approximate Electric Field Strength

    The figure shows the equipotential lines for another electric field. What is the approximate strength of the electric field at points A and B...
  35. N

    Equipotential Cylinder: Can Method of Images Work?

    An infinite string with linear charge density \lambda is put parallel to the axis of an infinite conducting grounded cylinder (V=0) of radius R, the distance between the string and the center of the cylinder is l. Find the potential outside the cylinder. Is it possible to solve this problem...
  36. G

    Equipotential Lines: Different Charge Magnitudes Explained

    If we suppose that the magnitudes of the charge distributions on the two rings are different. Is the mid line still an equipotential line? How can we explain this situation? Thanks..
  37. S

    Two or more different equipotential surfaces to intersect?

    I have two questions about electric field and equipotential surface. Here is first one: For an arrangement of two point charges, --Is it possible to find two points (neither at infinity) where E = 0 ? Secondly, --Is it possible for two or more different equipotential surfaces to intersect?
  38. D

    Equipotential Surfaces: Calculating Work Required to Move a Charge

    [SOLVED] Equipotential surfaces Homework Statement http://personalpages.tds.net/~locowise/test/equipot1.jpg Fig. 1 -- Some equipotential surfaces In the figure above, you see a set of equipotentials representing an electric field in the region and some labeled points (A..G). What is...
  39. P

    Equipotential Surfaces Question

    [SOLVED] Equipotential Surfaces Question If the radius of the equipotential surface of point charge is 14.3 m at a potential of 2.20 kV, what is the magnitude of the point charge creating the potential? have V = [1/4πεo] [q/r] Given that, V = 2.20kV = 2200V r = 14.3m...
  40. F

    Conductors and Equipotential Lines - Fun

    Conductors and Equipotential Lines - Fun! Homework Statement Consider the following two conductors. conductor A is grounded so that it has a voltage of 0 V and conductor B is charged up so it has a voltage of +20 V. Draw in the equipotential lines and then draw in the E field lines indicating...
  41. M

    Please explain equipotential surfaces/ contour maps

    Homework Statement Can someone please define contour map for equipotential surfaces in really simple terms. I understand that the potential diff is from the neg side I don't understand what it means when the lines are closer together? I thought the lines are just divisions of the voltage...
  42. B

    Equipotential Lines: Finding Voltage & Potential Errors

    if i am finding the equipotential lines by using a conducting sheet, power supply, and muiltimeter to find the voltage, what types of errors can be present while experimenting? could there be areas of no-flow or disappearing lines? thanks
  43. T

    Calculating Work on Equipotential Surfaces

    The work in joules required to carry a 6.0 C charge from a 5.0 V equipotential surface to a 6.0V equipotential surface and back again to the 5.0V surface is: A) 0 B) 1.2 X 10^-5 C) 3.0 X 10^-5 D) 6.0 X 10^-5 E) 6.0X10^-6 I was thinkin the work is 0, but then again that seems too easy
  44. S

    Which Point Requires the Most Work to Reach in an Electric Field?

    Homework Statement The work required to bring a negatively charged body from very far to either of the points indicated in the figure is greatest for point _____. a. point A b. point B c. point C d. point D e. point E Homework Equations...
  45. B

    Understanding Electric Field & Equipotential Surfaces

    Homework Statement If the electric field at a point in space has a magnitude of 300 volts/meter, about how far apart are the equipotential surfaces that differ by 10 volts? well, i think that they are 30 meters apart. All I did was 300 volts/meter/10 volts since that will cancel the...
  46. C

    Comparing Lab Results to Theory: Equipotential Lines Analysis

    Okay, we are supposed to do a lab in class and compare it to the real results. However, for some reason, my lab result is very different from my theoretical value. The lab is like this: I put a sheet of conductive paper with the dipole electrodes, one positive and one negative, of course...
  47. D

    Equipotential Lines and field mapping

    Equipotential Lines! I recently did a lab in class that dealt with electric field mapping (very similar to http://physics.nku.edu/GeneralLab/211%20Elect%20Pot.%20&%20Field%20Map.html) and i have to write a lab report now.. I don't understand why the equipotential lines are always perpendicular...
  48. B

    Equipotential planes and electric fields.

    Homework Statement Suppose a uniform electric field of magnitude 115.0 N/C exists in a region of space. How far apart are a pair of equipotential surfaces whose potentials differ by 2.0 V? Homework Equations 1 N/C = 1 V/m The Attempt at a Solution I know 115.0 N/C is the same...
  49. S

    Equipotential Lines: Field Uniformity & Electric Field Mapping

    A uniform electric field exists between parallel plates of equal but opposite charges. (Correct?) For electric field mapping with a general electric field mapping board, the electric field intensity, which can be calculated from the potential difference and distance between any two points, can...
  50. F

    Electric Field and Potential Change in a System with Equipotential Surfaces

    Problem: A given system has the equipotential surfaces shown below, where Vo = 12.0 V. (a) What are the magnitude and direction of the electric field? (b) What is the shortest distance one can move to undergo a change in potential of 5.00 V? I am not too sure on what equations I...
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