What is Electric force: Definition and 247 Discussions

Electromagnetism is a branch of physics involving the study of the electromagnetic force, a type of physical interaction that occurs between electrically charged particles. The electromagnetic force is carried by electromagnetic fields composed of electric fields and magnetic fields, and it is responsible for electromagnetic radiation such as light. It is one of the four fundamental interactions (commonly called forces) in nature, together with the strong interaction, the weak interaction, and gravitation. At high energy, the weak force and electromagnetic force are unified as a single electroweak force.

Electromagnetic phenomena are defined in terms of the electromagnetic force, sometimes called the Lorentz force, which includes both electricity and magnetism as different manifestations of the same phenomenon. The electromagnetic force plays a major role in determining the internal properties of most objects encountered in daily life. The electromagnetic attraction between atomic nuclei and their orbital electrons holds atoms together. Electromagnetic forces are responsible for the chemical bonds between atoms which create molecules, and intermolecular forces. The electromagnetic force governs all chemical processes, which arise from interactions between the electrons of neighboring atoms. Electromagnetism is very widely used in modern technology, and electromagnetic theory is the basis of electric power engineering and electronics including digital technology.
There are numerous mathematical descriptions of the electromagnetic field. Most prominently, Maxwell's equations describe how electric and magnetic fields are generated and altered by each other and by charges and currents.
The theoretical implications of electromagnetism, particularly the establishment of the speed of light based on properties of the "medium" of propagation (permeability and permittivity), led to the development of special relativity by Albert Einstein in 1905.

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  1. A

    Electric Fields: Oscillating point charge

    Homework Statement Reading a journal from that crazy old retired physics professor on the hill, you stumble upon a scheme to generate high frequency (HF) radio waves (λ = 10 m). It requires generating an electric field that diverges from a point and increases in strength linearly with respect...
  2. NotADuckFan

    Relationship between electric energy and force

    Homework Statement One of the three types of radioactive decay is "β decay", during which protons decay into neutrons or viceversa, emitting either electrons (β) or positrons (β+) at high velocity as a result. In one experiment, a β source and β+ source are placed 10 cm apart from each other...
  3. W

    Expansion, Gravity and the Electric Force

    The explanation as to why galaxies like the Milky Way and Andromeda are not expanding away from each other is that they are gravitationally bound, and the expansion at that small scale is not really apparent anyway. My question is purely hypothetical. What if you had a measuring stick that...
  4. K

    Direction of Electric Force in a E. Field?

    Is the electric force negative when it is in opposite direction as the electric field? If it is, a positive charge would always have a positive E. force? thanks.
  5. M

    Charged particle accelerates in an electric field?

    Homework Statement A positively charged particle initially at rest on the ground accelerates upward to 200m/s in 2.60s. The particle has a charge-to-mass ratio of 0.100 C/kg and the electric field in this region is constant and uniform. What are the magnitude and direction of the electric...
  6. S

    Net Electric Force Homework: Find Negative Charge Position

    Homework Statement [/B] In the above figure, if Q1 and Q2 are positive, where could a negative charge be placed and have a vertically upward net force on it? Homework Equations F = k|q||q| / (r^2) The Attempt at a Solution I wrote the force equations for the negative charge and both positive...
  7. R

    Need of small charge in definition of electric field?

    Why do we need infinitesimally small charge in definition of electric field? Since the test charge cannot exert force on itself, F on test charge will not change whatever the value of test charge q is. So, F/q will be same for any value of test charge. Then why do we need this limit of...
  8. S

    Hydrogen bonding force problem

    Homework Statement In a DNA molecule, the base pair adenine and thymine is held together by two hydrogen bonds (see figure below). Let's model one of these hydrogen bonds as four point charges arranged along a straight line. Using the information in the figure below, calculate the...
  9. genxium

    Is it able to make point charges stationary by electric force?

    First by "stationary" I mean "with respect to each other" so as to avoid introducing relativity problems. I'm wondering whether there's a way to prove or disprove that given N > 1 point charges q_1, q_2, ..., q_n, is there always a way of putting them in 3-dimensional space such that all of...
  10. U

    Radius of object in electric field

    Homework Statement Two parallel plates with opposite charges are 0.01 m apart and have a potential difference of 100 V. A charged spherical object has 20 excess electrons stays motionless between the plates. If the density of the object is 1000 kg/m^3, what is the radius of the spherical...
  11. N

    Magnitude of the electric force a hydrogen nucleus exerts on electron?

    Homework Statement What is the magnitude of the electric force a hydrogen nucleus exerts on its only orbiting electron in the Bohr model? The Attempt at a Solution Fe = kQq/r^2 Since there is one proton and one electron. Q and q are equal to each other: 1.6 x 10^-19. k = 9 x...
  12. S

    Electric Force: Equilateral Triangle

    Homework Statement Three charges, +Q, +Q, and -Q are placed at the vertices of an equilateral triangle of length "s" on a side. Find the magnitude and direction of the force on one of the +Q charges. Homework Equations ForceElectric=(K*q1*q2/d2) The Attempt at a Solution I've set...
  13. C

    Electric force inside a cylinder(my friends and I can't solve this

    Electric force inside a cylinder(my friends and I can't solve this:( Homework Statement A right circular cylinder has radius R and length L, and a nonuniform volume charge density ρ(\hat{r}). If the z axis is chosen to coincide with the axis of the cylinder, the charge density is ρ(\hat{r})...
  14. C

    Work done by electric force on a point charge in a cylinder?

    Homework Statement A point charge q is moved inside a hollow charged cylinder of radius R. The initial point A is a distance (3/4)R from the center and the final point B is at the center of the sphere. How much work is done by the electric force in this case? 2. The attempt at a solution I...
  15. B

    Electric Force problem involving HCl and Br- on coordinate axis

    Homework Statement A hydrogen chloride molecule (HCl) has a partial positive charge on the hydrogen atom and a partial negative charge on the chlorine atom. The HCl molecule is placed at A. There will be force on the bromide ion in the +x direction. B. There will be force on...
  16. barryj

    Concept question about electric force

    If I comb my hair with a rubber comb, the comb can be used to pick up small bits of paper on a desk. This says that there is a force between the comb and the paper bits. If the paper bits are uncharged why are they attracted? You can pick up paper bits by pulling a piece of scotch tape frm a...
  17. E

    Faraday's Law and electric force

    I'm working on personal research problem while taking leave from school to work a Co-op. The basic idea of what I'm trying to create is a device that will produce electrical charge without having to be charged or have some outside dependence of electric force. the only way I could think to do...
  18. C

    Trouble with electric force question

    Homework Statement I'm having a little trouble with an electric force question I have been working on. It seems simple, but my answer keeps coming out incorrect. Using the graph, deduce the electric force vector on charge q3 by q1/2. In case it is not clear, q3 lies on point (2,2)...
  19. A

    Electric force of attraction between forces.

    Problem: What is the electric force of attraction between charges of 3 C and -10 C separated by a distance of 5 m? Equation: F= k x (Q x q / r^2) 3 x -10 / 5^2 = -1.2 x 8.99E9 = 1.08 E10 N. Using this equation and the answer I found, I still am getting the wrong answer. Not sure what...
  20. D

    Electric force charges homework

    1. A student is performing an experiment with two identical small metal balls, A and B. Initially, Ball A contains 6.0-uC net charge with unknown sign and Ball B is neutral. The student brings them in contact and then separated them by 20cm. Both of the balls are remained isolated. Is the...
  21. D

    Magnitude of the electric force?

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  22. M

    Electric force in an electric field.

    Generally I would type out the question myself rather than just screenshotting it but since I'm on my phone I elected to simply attach pictures of both the question and my work. Part a and b I was able to do, but what I'm having a hard time with is part c. I know how to find the electric force...
  23. G

    Coulomb's Law and Electric Force

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  24. M

    Electric field between 2 objects and electric force on object?

    Homework Statement Suppose two metal plates are separated by 1.00 cm. These plates are wide: at least 0.5 m square. We hook wires from a battery to each plate, so that there is a potential of 500 volts between them. Homework Equations (A) Find the electric field between the plates, in the...
  25. G

    Effect of media on electric force

    I was thinking about the following: Assuming that you have NON SPHERICALLY SYMMETRIC charges and they are both in medium 1. Does it make a difference(whereby I am referring to the total force between these two charges) if there is a second medium 2 in the local area of both? So both charges are...
  26. W

    Magnitude of the Electric Force on q

    1. If a = 3.0 mm, b = 4.0 mm, Q1 = -60 nC, Q2 = 80 nC, and q = 30 nC in the Figure Q1, what is the magnitude of the electric force on q? 2. F = kq1q2/r^2 Coulomb’s Law 3. Answer is F=1.0N I'm a beginner in electrical study, i stuck on the net force. My steps are: F1=kQ1Q2/a^2 , F2= kQ2q/r^2
  27. J

    Electric force between objects that are in brief contact

    Homework Statement Two small charged objects of the same mass and volume are brought into brief contact with each other. If the initial charges on the two objects are -3.00 x10^-6 and -1.50 x10^-6, what is the electric force between the objects when they are separated to a distance of 0.500m...
  28. R

    Electric Force of charges A,B,C on another charge

    Homework Statement A, B and C have charges of -2.6, 8.5, and 7.5 microC respectively. These charges are at the points 2.5, 7 and 2 on a straight line where all distances are measured in millimeters from the zero point. What force does a -7.5 microC charge feel if it is at the point 1.2 mm...
  29. M

    Three Point Charges, find the electric force exerted

    Homework Statement Three charges, each of magnitude 2 nC, are at separate corners of a square of edge length 1 cm. The two charges at opposite corners are positive, and the other charge is negative. Find the force exerted by these charges on a fourth charge q = +3 nC at the remaining (upper...
  30. R

    Electric Force and Field Strength Problem

    Three charges are located on a coordinate plane scaled off in meters. Charge #1 is 5 nC and located at (0,0). Charge #2 is -3.0 nC and located at (0,-.10). Charge #3 is 6.0 nC and is located at (-3,0). a) What is the net force (magnitude and direction) on the charge at the origin? b) What is...
  31. S

    What is the net electric force on the charge at the origin?

    Homework Statement Consider three charges in a triangle as shown. 1. What is the net electric force on the charge at the origin? 2. What is the direction of this force(between -180 and 180)? 3. What is the magnitude of the net electric field at the position of the charge at the...
  32. R

    Finding r using point charges and work done by an electric force

    Homework Statement A positive point charge (q = +8.9 10-8 C) is surrounded by an equipotential surface A, which has a radius of rA = 1.3 m. A positive test charge (q0 = +2.7 10-11 C) moves from surface A to another equipotential surface B, which has a radius rB. The work done by the electric...
  33. Q

    Electric Force Textbook error?

    Homework Statement Find the net force given a point charge and the value of the electric field. Homework Equations FE = εq ε= (5.6*10^4) q=(-1.2 * 10^-5) The Attempt at a Solution FE = εq FE = (5.6*10^4)(-1.2 * 10^-5) FE = 0.672 N [left] Seriously. I am posting this...
  34. A

    How are the gravitational and electric force comparable?

    I hear all the time how the electric force is so much stronger than gravity. I understand both forces are inversely proportional to the distances squared, and that the gravitational constant is roughly 10^20 times greater than the coulomb constant. But one involves charges, while the other...
  35. J

    Electric Force on a charged conductive body

    Hi, how to calculate the force on a charged conductive body (ball), when that body is between two parallel plates (+V, -V) (see image), ooh and I am calculating numerically. I would first calculate the surface charges on the conductive surfaces (2 disks + ball), then calculate the potential...
  36. W

    Find the electric force on the proton

    Homework Statement Homework Equations magnitude of the force is k(e^2)/(r^2) k = 9 * 10^9 N*m^2/C^2 e = 1.6 * 10^-19C The Attempt at a Solution ke^2/(r^2) = (9*10^9 N * m^2/C^2)(1.6*10^-19C)^2/(.39^2 + .40^2)*10^-18m^2 = 7.38 *10^-10 N
  37. B

    What is the electric force of the molecule on the proton?

    Homework Statement An ammonia molecule (NH3) has a permanent electric dipole moment 5.0 x 10^-30cm. A proton is 2.50nm from the molecule in the plane that bisects the dipole. What is the electric force of the molecule on the proton? Homework Equations F = QE = eE_yj =...
  38. N

    Direction of the torque of the electric force

    Homework Statement http://i.imgur.com/YMuGM.png Homework Equations \tau = F * r The Attempt at a Solution I don't know how to do these types of problems. My professor didn't even go over this. He just said to use that formula to find the answer. I know the electric field...
  39. A

    How can you solve an electric force problem with vectors?

    Homework Statement http://imageshack.us/a/img145/3799/img0302ok.jpg Homework Equations f=k*q1q2/r^2 The Attempt at a Solution i just don't know how to start i just need a hint and i will do the rest
  40. D

    Coulomb's constant, electric force constant

    Coulomb's Law states F = q**2/ r**2 q= statCoulombs In SI units, F = Ke (q**2/r**2) q= Coulombs I read that 1 C = 2.997 x 10E+09 statC Then Ke = 8.987 x 10E+09 (1) Does anyone know where the conversion for C to statC came from? (2) and how you get the Ke from those values...
  41. I

    Work done by an electric FIELD = Work done by electric FORCE ?

    "Work done by an electric FIELD" = "Work done by electric FORCE"?? Homework Statement Problem 1 If the electric field does negative work on a negative charge as the charge undergoes a displacement from position A to position B within an electric field, then the electrical potential energy...
  42. D

    How to find net electric force of zero

    I was wondering if someone could help me with this question: A charge 3q is at the origin, and a charge -2q is on the positive x-axis at x = a. Where would you place a third charge so it would experience no net electric force? I currently set up two equations: 1. 3q*q/b^2 where b is...
  43. M

    Calculating Electric Force: 2 Electrons & a Proton

    Homework Statement Take a look at this image first If two electrons are each 2.50×10−10 from a proton, as shown in the figure, find the magnitude and of the net electrical force they will exert on the proton. Homework Equations The Attempt at a Solution k=1/4πε0 So what...
  44. S

    What is the Electric Force in Equilibrium?

    Homework Statement Two identical conducting small spheres are placed with their centers .300 m apart. One is given a charge of 12.0 nC and the other is given a charge of -18.0nC. a) Find the electric foce exterted on one sphere by the other. B) the sphers are connected by a conducing wire...
  45. B

    Solving for Electric Force Balance in a Suspended Sphere Setup"

    First of all, hey everyone. I was wondering if any of you could help me solve this. I've tried but i keep getting insane equations so I might be doing something wrong. Two equal spheres with a mass of m have equal charges q. They're suspended by two ropes with length L in points distanced d...
  46. S

    Relation of Magnetic and Electric Force of particles in vacuum

    Homework Statement There are two particles side by side in a vacuum with electric charge q and mass m, traveling at distance d apart, with v speed(less than speed of light). What is the ratio of magnitude of magnetic to electric force the particle exert on each other? Homework Equations...
  47. M

    How Do I Correctly Calculate the Electric Force Vector Direction and Magnitude?

    Homework Statement http://postimage.org/image/y4h1ubp8b/ Homework Equations F_xy=(k*q*q)/r^2 The Attempt at a Solution This is a problem involving Electric Force: http://postimage.org/image/y4h1ubp8b/ My goal is to find the direction and magnitude of q1. However, every...
  48. D

    Why is it important to not delete posts after receiving help?

    Solved.
  49. A

    Electric Force, Equilibrium Config of Charges

    Homework Statement Find the charge Q that should be placed at the centre of the square of side 8.50E+0 cm, at the corners of which four identical charges +q = 3 C are placed so that the whole system is in equilibrium.Homework Equations F=(k*q1*q2) / r^2 The Attempt at a Solution I know the...
  50. lonewolf219

    Findng electric force for line of charge

    Homework Statement Find the force acting on an electron located "d" distance from the midpoint of a line of charge, length "L", located on the x axis. The line of charge is positive. Homework Equations F(e)=kq1q2/r^2 The Attempt at a Solution λ=linear density, here the charge is...
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