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. M

    Electric potential question

    If the pos charged particle moves from point 1 to 2 I believe that the electric potential energy will increase. My reasoning for this is because I know electric potential energy is found by knowing how much work it takes to move a charged particle from point 1 to point 2. Because a pos charge...
  2. A

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  3. B

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    Homework Statement The electric potential V in a region of space is given by the following expression, where A is a constant. V(x, y, z) = A (6x^2 - 7y^4 + 6z^2) (a) Derive an expression for the electric field vector E at any point in this region. (Use the following as necessary: A, x, y, and...
  4. C

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    Homework Statement Two metal balls of mass m1 = 2 g (diameter = 2 mm) and m2 = 6 g (diameter = 6 mm) have positive charges of q1 = 2 nC and q2 = 7 nC, respectively. A force holds them in place so that their centers are separated by 8 mm. What will their velocities be after the force is...
  5. S

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    A charge of -2.580 mu C is located at (2.575 m, 4.742 m), and a charge of 1.440 mu C is located at (-2.730 m, 0). Find the electric potential at the origin. q_1= -2.580*10^-6 C q_2= 1.440*10^-6 C k = 8.99*10^9 N*m/C^2 r_2= -2.730 m V= (k*q_1)/r_1 + (k*q_2)/r_2 So first i...
  6. C

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  7. D

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  8. D

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  9. E

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  10. M

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    Homework Statement The four 2.23 g spheres shown below have q+ve=15.0 nC and d=3.28 cm. The spheres are released simultaneously and allowed to move away from each other. What is the speed of each sphere when they are very far apart...
  11. S

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    This is more of a question about a concept than the actual homework problem. The homework problem gives diagrams of rods with varying charge densities, but there's one important concept I don't yet understand, and it's stopping me from moving on in the problem. My question is even more...
  12. M

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    Homework Statement An electron is released from rest on the axis of a uniform positively charged ring, 0.174 m from the ring's center. If the linear charge density of the ring is +0.150 nC/ m and the radius of the ring is 0.348 m, how fast will the electron be moving when it reaches the center...
  13. M

    Electric potential of two spherical shells

    1. Homework Statement [/b] Consider two thin, conducting, spherical shells as shown in cross-section in the figure below. http://capa.physics.mcmaster.ca/figures/sb/Graph25/sb-pic2565.png [b] The inner shell has a radius r1 = 17.2 cm and a charge of 10.3 nC. The outer shell has a radius r2 =...
  14. M

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    Homework Statement Two concentric spherical conducting shells of radii a = 0.360 m and b = 0.540 m are connected by a thin wire, as shown in the figure below. http://capa.physics.mcmaster.ca/figures/sb/Graph25/sb-pic2550.png If a total charge Q = 10.6 µC is placed on the system, how much...
  15. K

    Derive equation for electric potential of electric dipole

    I'm not understanding how the equation of the electric field due to an electric dipole is derived. This is how my book derives it: Say you have electric dipole composed of charges +q and -q a distance d apart, with the negative charge at the origin of the z-axis. Then, at any point z, the E...
  16. P

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    Homework Statement 10. If an electron is released from infinity, how fast will it be traveling after falling to within 10-8m of a charge q of 4.8*10-19? a. 1.32*104m/sec b. 8.7*104m/sec *c. 2.76*105m/sec d. 4.01*105m/sec Homework Equations ΔU=ΔVq V=kq/r conservation...
  17. M

    Electric Potential due to a charged conductor

    Homework Statement Two charged spherical conductors are connected by a long conducting wire, and a charge of 22.0 µC is placed on the combination. If the first sphere has a radius of 4.49 cm and the second has a radius of 5.68 cm, what is the electric field near the surface of each sphere...
  18. P

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    Homework Statement Two charges q = 4.0μ C are fixed in space a distance d = 4.0 cm apart, as shown in the figure. With V = 0 at infinity, what is the electric potential at point C? You bring a third charge q = 4.0μC from infinity to C. How much work must you do? What is the potential...
  19. H

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  20. S

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  21. S

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  22. atomqwerty

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  23. H

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    Homework Statement Two frictionless pucks are placed on a level surface as shown, at an initial distance of 20m. Puck 1 has a mass of 0.8 kg and a charge of + 3x10^-4 while puck 2 has a mass of 0.4 kg and a charge of +3 x10^-4. The initial velocity of puck 1 is 12 m/s [E] and the...
  24. A

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  25. J

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  26. L

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  27. C

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  28. T

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  29. S

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  30. H

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    I am confusing about dealing with the vectors in integral boundaries of the electric potential; ^{b}_{a}∫E.ds where a and b are vectors. For example, if I would calculate the potential for outside region of a sphere along z-direction, I would use E=\frac{ρR^3}{3ε_{0}z^2}\hat{z}, and...
  31. A

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  32. M

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  33. M

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  34. J

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  35. I

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  36. P

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  37. T

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  38. J

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  39. B

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  40. L

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    Homework Statement I have an expression for electric potential. Can I multiply this by mass to turn it into potential energy? Homework Equations W=Fs ? The Attempt at a Solution
  41. E

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  42. J

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  43. B

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  44. L

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  45. Telemachus

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  46. N

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  47. A

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  48. L

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    Given the following problem: An electric dipole has charge +Q at position a and charge –Q at position -*a along the z axis. a. Calculate the electric potential at an arbitrary point. Choose the arbitrary constant so at V=0 at infinity. Express the result in terms of r and θ (radius and polar...
  49. S

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