Electric force Definition and 247 Threads

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. paulimerci

    Find the magnitude of the electric force from 3 charges at vertices of a cube

    There are three charges with +1 μC and −1 μC, are placed at the opposite corners of a cube with edges of length 1 cm, and the distance from P to B is 1cm 2. I labeled them as A, P, and B, which is shown in the diagram below. Since we need to find the magnitude of the charge at point P and the...
  2. Pushoam

    Electric force on the charge kept at the centre of a metallic shell

    Hence the electric force on the charge in both cases is zero. Is this correct?
  3. M

    Magnitude of external electric force on electric dipole

    For this part(b) of this problem, how is the magnitude of the total electric force zero? I thought it would be: If they asked for the total electric force, then I would have said zero because the two electric force vectors cancel. Many thanks!
  4. josephsanders

    I Tangential electric force at a surface

    Suppose you have an infinite plane of charge. If the surface charge density is uniform, would the tangential electric force always be zero, even if it is not a conductor nor static? My thought process for this is that if you look at each point charge and draw the electric field lines, then at...
  5. A

    I If we take two charges and hold one still, what are the forces?

    If we take two positive charges +q1 and +q2, and we hold q1 still, does q2 experience a repulsive force due to q1 repelling q2 AND a repulsive force due to q2 repelling q1? That is ##|F| = 2*\frac{k*q1*q2}{r^2}##
  6. LCSphysicist

    Electric force due to a moving charge

    I am having some problems involving the force that a source moving with speed v along the x-axis would exert on a test charge at the x axis. Moving to the frame of the source charge, we got that the electric field it exerts is $$E' = kq/x'²$$ Now, moving back to the lab frame, and considering...
  7. Z

    Understanding the electric force felt by the charges on a sphere

    A thin shell in reality doesn't have zero thickness. Consider the image below, showing a cross-section of a small portion of the shell: Here we are considering a more general case in which we have electric fields of magnitude ##E_1## and ##E_2## on each side of the shell. Gauss's Law...
  8. Viona

    Why Doesn't Electric Force Cause Wires to Move?

    Hello, In the section of Magnetic Force on a Current- Carrying Conductor in the book of College Physics by Serway, it is written that the Current- Carrying Conductor in a magnetic field deflects because the magnetic force on the electrons transfers to the bulk of the wire due to the collisions...
  9. wcjy

    Electric field problem using Gauss' law: Point charge moving near a line charge

    F = qE ma = (2*10^-6) * (λ / (2pi*r*ε0) ) ma = (2*10^-6) * (4*10^-6 / (2pi*4*ε0) ) => I am not certain what to put for r ( But I sub in 4 because dist is 4) a = ( (2*10^-6) * (4*10^-6 / (2pi*4*ε0) ) )/ 0.1 a = 0.35950 v^2 = U^2 + 2 a s v = 0 u^2 = -2 a s => Can't sqrt negative so...
  10. E

    Net electric force of multiple charged particles in 3-d space

    I draw the graph like this: For (b), I divided each force vector to e from p1 and p2 as x and y parts. I computed them and got Fx=-4.608*10^(-15)N Fy=-2.52*10^(-15)N However, I am not sure whether I did it correctly or not... I appreciate every help from all of you! Thank you!
  11. P

    What causes an electric force in one situation but not in another?

    Hi, I'm dealing with a more or less trivial question. Let's have a look on two situations. Consider a (negative) charged metal plate. If the plate is infinit in size it will produce a perfekt homogeneous electric field. If we now place a second plate parallel to the first one the electric...
  12. Flaming Physicist

    Electric force between two equal parallel rings of charge

    The problem is symmetric around the z axis, thus the force must be in the z direction only. I tried dividing both rings into differential elements, then integrating through the upper ring to get the z component of the total force on the upper ring due to a differential element of the lower ring...
  13. Achintya

    What is the reality of the Electric Force & Field?

    Please help. Thank you.
  14. B

    Electric Force and Field homework problem

    This is my homework. And we don't have online lessons. But my teacher gave this for homework. I couldn't solve this problem. Can you help me?
  15. adamaero

    Understanding Electric Force on Q in Relation to Distance d and Charge Q1

    x^2 + d^2/4 = d^2 x = sqrt(3d^2/4) F_1x = sqrt(3)*d*k*Q1/2. In the solution, where did the "d" in the numerator go?? Is my math wrong?
  16. H

    The effect of an external substance on the electric force between two charges

    How does the force between the two opposite charge change if we place a substance (conductor, insulator, ...) between them? It seems that the force between the two charges doesn't change but the total force on each charge increases because of the superposition of the original field of the other...
  17. Mutatis

    Net force acting on a charged particle ##+Q##

    Homework Statement Twelve equal particles of charge ##+q## are equally spaced over a circumference (like the hours in a watch) of radius R. At the center of the circumference is a particle with charge ##+Q##. a) Describe the net force acting over ##+Q##. b) If the charge located at...
  18. CDL

    Point Charges on a Polygon with another Charge in the Middle

    Homework Statement Suppose we have a regular n-gon with identical charges at each vertex. What force would a charge ##Q## at the centre feel? What would the force on the charge ##Q## be if one of the charges at the vertices were removed? [/B]Homework Equations Principle of Superposition, the...
  19. H

    Electric Force on a Charge in a Solenoid

    Homework Statement [IMG]http://[url=https://ibb.co/dgUy6T]https://preview.ibb.co/iyqS0o/20180525_213806.jpg Since i only know the field direction, increasing go into page. Why the answer is C? Why the answer "a" ? The R and r on the pic is respected to what? Homework EquationsThe Attempt...
  20. C

    What Is the Net Electric Force and Field on Charge 1?

    Homework Statement A) Determine the net force on charge 1. B) What is the net electric field acting on charge 1? Homework Equations Fnet Enet The Attempt at a Solution Let North and East be positive. Because of symmetry, F21 = F31 F2 = F3 F2 = (9.0x109)(2.0x10-5(3.0x10-5) / (2.0m)2 F2...
  21. T

    How exactly does the electric force act?

    greeting How exactly the electric force acts .The definition of force is In physics, a force is any interaction that, when unopposed, will change the motion of an object. as the electron circulates around the nucleus of the atom because of that I do not see how that force acts .
  22. G

    Help finding component of electric force

    Homework Statement [/IMG] In this problem I am trying to understand the solution for finding the net force on charge 3 due to charge 1. However, I am getting stuck already on F31x. Homework Equations F=kqq/r^2 The Attempt at a Solution I found theta by tan-1(0.5/1)=26.565degrees r= sqrt...
  23. Z

    Coulomb's force - magnitude of the electric force

    Homework Statement Show that the magnitude of the electric force on each ball is given by Fe = mgtanθ/ (cosα+ sinαtanθ) where θ = arcsin(x2/L) α = arcsin((y2-y1)/r) r = √((x2-x1)^2+(y2-y1)^2) This is a question from my coulomb's law lab, where 2 styrofoam balls where charged, one was hung on a...
  24. E

    Resolving the electric force into x y components?

    Homework Statement A 64 microC charge is locate 30 cm to the left of a 16 micro C charge. What is the resultant force on a -12 micro C charge positioned exactly 50 mm below the 16 micro C charge?Homework Equations coulomb law f=k*qq/(r^2),resultant force,resolve into x and y component. The...
  25. Y

    Electric force calculate the separation

    Homework Statement two charges with the same charge q and mass m are moving with the same acceleration at each instant. calculate the separation between them. Homework EquationsThe Attempt at a Solution F=kqq/r^2 so, F= k q^2/r^2 r^2=kq^2/F let the acceleration be a, then F=ma. r= q√k/F...
  26. jlmccart03

    Finding magnitude and direction of net force on a dipole.

    Homework Statement A dipole with charges ±q and separation 2a is located a distance x from a point charge +Q, oriented as shown in the figure. Part A: Find an expression for the magnitude of the net force on the dipole in the limit x≫a. Part B: What is the direction of the net force...
  27. P

    What is the net electric force exerted on the point charge q1?

    Homework Statement Given that q = 20 µC and d = 11 cm, find the direction and magnitude of the net electric force exerted on the point charge q1 below. Homework Equations F(elect) = k (q1,q2)/d^2 The Attempt at a Solution 1. after converting each unit to its appropriate form, F(net...
  28. jlmccart03

    Electric Forces and net electric force?

    Homework Statement Problem # 4:[/B] A thin semicircular rod has a total charge +Q uniformly distributed along it. A negative point charge -Q is placed as shown. A test charge +q is placed at point C. (Point C is equidistant from -Q and from all points on the rod.) http://imgur.com/AeVfddb Let...
  29. H

    How to determine the magnitude of the electric force

    Homework Statement A piece of tape is pulled from a spool and lowered toward a 170-mg scrap of paper. Only when the tape comes within 8.0 mm is the electric force magnitude great enough to overcome the gravitational force exerted by Earth on the scrap and lift it. Determine the magnitude and...
  30. L

    Net electric force and Net electric field

    Homework Statement a) Find the net force on charge 1. b) What is the net electric field acting on charge 1? Please see the attached files to view the image that goes with the questions above. Homework Equations I'm having trouble with this unit in general and I'm not to confident in these...
  31. Abwi

    Can the Sphere of Radius 'a' Be Modeled as a Point Particle?

    Homework Statement [/B] Find the electric force between the two spheres. Sphere r=b-a has a volumetric density of p=K, where K is a constant Sphere r=a has a volumetric density of p=θ*r Homework Equations As you can see the sphere of radius 'a' doesn't have a uniform electric field because...
  32. NihalRi

    Electric force and electrons transfered

    Homework Statement In a group assignment we had to find out how many electrons were transferred to pieces of tape after we pealed them of a table. The second part of the project asked us to imagine that one piece of tape was a distributed charge and that the other was still a point charge...
  33. NihalRi

    Electric force, theory and algebra.

    Homework Statement This question has two parts. There is a quarter or radius R that is charged with a net force of Q. A point like charge of net charge q,is at a distance z from the center of the quarter. Q1: Under what condition could we use Coulomb's law to find the magnitude the force...
  34. Aldo Biko

    The force between charged and neutral object

    Homework Statement I did a lab involving Van de Graaff generator. Basically, below the charged sphere, I put a neutral sphere on a scale and measure the difference in mass which then I can calculate the force acting on the neutral sphere. I repeated the experiment with different distance. What...
  35. C

    Draw a free body diagram for the electric force

    Homework Statement A positive charge Q1=7.4uC is located at a point X1=-2 m, a negative charge Q2=-9.7uC is located at a point X2=3m and a positive Q3=2.1uC is located at a point X3=9 A. Draw a free body diagram for the electric force acting on Q1, Q2, and Q3. B. Find the magnitude of the force...
  36. Clara Chung

    What Is the Value of Point Charge q in a Square Configuration?

    Homework Statement PQRS is a square. Three point charges -Q, +Q and -3Q are fixed at P, Q and S respectively as shown. A point charge q is then placed at R and it experiences a net electric force towards S. Which of the following is equal to q? photo ...
  37. A

    Electric Force and Superposition...Help

    Homework Statement Two equal positive charges, both q = 2.0 × 10−6 C, interact with a third charge, Q = 4.0 × 10−6 C, as shown in the figure above. What is the magnitude of the electric force on Q? (kC = 8.99 × 109 N•m2/C2) Homework Equations I'm confused about assigning signs when I get to...
  38. A

    Struggling with Electric force.... The Superposition Principle

    When I'm solving a superposition principle problem i get stuck and so confused with the signs. For example this problem Consider three point charges at the corners of a triangle, as shown at right, where q1 = 6.00 × 10−9 C, q2 = −2.00 × 10−9 C, and q3 = 5.00 × 10−9 C. Find the magnitude and...
  39. henrco

    Find the electric force on a point charge

    Homework Statement A point charge q1 = 4.40 μC is at the origin and a point charge q2 = 6.00 μC is on the x axis at x = 2.49 m. i) Find the electric force on charge q2 ii) Find the electric force on charge q1 Homework Equations Coulomb's law F = k (q1q2)/d^2 The Attempt at a Solution Part...
  40. H

    Electric fields between parallel plates

    Homework Statement Two large parallel plates are 0.8 m apart and generate an electric field of 12 N/C between them. At 0, 1/4, 1/2, 3/4, and full distance (0.8m), how much kinetic energy does a +0.25 C charge gain as it passes through each location? Homework Equations V = PE/q The Attempt...
  41. H

    How Does Charge Affect Motion in Outer Space?

    Homework Statement In outer space, a ball with mass 0.25kg and charge +4/K C is shot from 5m towards a +0.5C charged ball with an initial velocity of 20 m/s What main Physics principle should be used to solve this problem? What is the closest the small ball will get to the large one? What is...
  42. C

    Equation for the energy of an electron

    Hello, I would like to thank all of the contributors on this site. You have helped me in more ways than I can count. I am struggling with the following concept and was wondering if anyone could clarify this. As the electron gets further away from the nucleus, its energy increases. This makes...
  43. C

    Calculating Velocity in a Charge/Field Interaction: A Homework Challenge

    Homework Statement Homework Equations F=kqQ/D^2=Ma E=kQ/D^2 D=vt? The Attempt at a Solution So far, I've been able to label the forces on each ship through superposition. But that is all I currently able to understand. I know that my end solution is a speed/velocity, but I am not sure how to...
  44. C

    A positively charged wire bent into a semi-circle

    Homework Statement A positively charged wire is bent into a semicircle of radius R, as shown in the figure below. The total charge on the semicircle is Q . However, the charge per unit length along the semicircle is non-uniform and given by λ=λocos(θ) What is the relationship between λo, R...
  45. C

    Calculating Electrostatic Force on a Suspended Gossamer Spider

    Homework Statement You are studying Gossamer Spiders in a biology research lab and marvel at their ballooning stunts. These Spiders disperse by spinning strands of silk in open air. The flight of these spiders is electrostatic in nature because everything that moves through air develops static...
  46. Antonius

    Electric force (varying) on q from Q (conceptual question)

    Let's say Q is a charge at fixed position on the x - axis. There is another identical charge q on the y - axis. There is an electric force acting on q from Q (and it's not constant.) My question is can I find force acting upon q from Q to move q to a certain distance "a" , along y - axis...
  47. P

    Electric force-finding coordinate

    Homework Statement The y-axis marks the boundary between the area where the is no electric field (in the second and third quadrant) and the area where there is a constant electric field: E = 610j N/C (in the first and fourth quadrant). An electron travels along the negative x-axis toward the...
  48. H

    Electric Force: Magnitude & Direction Calc.

    Homework Statement Calculate the magnitude and direction of the electric force if a charge of −3.5 × 10−7 C is placed in a field of 12 N/C Homework Equations e = Fe/q The Attempt at a Solution I just plugged in values into the equations to find Fe and my answer was negative so the force is...
  49. E

    Electric Force and Work Question

    Homework Statement Three identical particles, each possessing mass m and charge +q, are placed at the corners of an equilateral triangle with side r. The particles are simultaneously set free and start flying apart symmetrically due to coulomb's repulsion forces. The work performed by Coulomb's...
  50. S

    Magnitude of electric force on a proton

    Homework Statement Two protons are 2.5fm apart. What is the magnitude of the electric force on one proton due to the other proton? Homework Equations Fe = K|q1||q2| / r2 The Attempt at a Solution Fe = (9 x 109)x(1.6 x 10-19)2 / (2.5 x 10-15)2 Fe = 37 N I got the answer but I don't...
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