Electrostatic fields Definition and 16 Threads

An electric field (sometimes E-field) is the physical field that surrounds electrically-charged particles and exerts force on all other charged particles in the field, either attracting or repelling them. It also refers to the physical field for a system of charged particles. Electric fields originate from electric charges, or from time-varying magnetic fields. Electric fields and magnetic fields are both manifestations of the electromagnetic force, one of the four fundamental forces (or interactions) of nature.
Electric fields are important in many areas of physics, and are exploited practically in electrical technology. In atomic physics and chemistry, for instance, the electric field is the attractive force holding the atomic nucleus and electrons together in atoms. It is also the force responsible for chemical bonding between atoms that result in molecules.
Other applications of electric fields include motion detection via electric field proximity sensing and an increasing number of diagnostic and therapeutic medical uses.
The electric field is defined mathematically as a vector field that associates to each point in space the (electrostatic or Coulomb) force per unit of charge exerted on an infinitesimal positive test charge at rest at that point. The derived SI units for the electric field are volts per meter (V/m), exactly equivalent to newtons per coulomb (N/C).

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  1. cianfa72

    I Charging a small metal ball from a charged hollow sphere

    I keep reading the amusing lectures from Feynman on Electrodynamics. In particular in Lecture 5-8 figure 5-10, he argues that touching a charged hollow sphere externally with a litte metal ball will cause the ball to pick up charge from the charged sphere (contrary touching the hollow sphere...
  2. A

    B Can charges move without a field? How charges redistribute without it?

    So from Gauss theorem, electric field at any point inside a uniformly charged sphereical shell is zero. Thus there is no electrostatic force on the inner sphere. From what I have learnt, a field is necessary to move charges. But in this case the inner sphere acquires a charge q without any...
  3. F

    I How can electrostatic fields be composed of photons?

    I know little about QED, QCD, and whatever the corresponding theory for the weak force is, and of course virtually nothing about the quantized theory of the gravitational force, which mostly doesn’t exist, so the following arguments and questions may be somewhat wrongly based where they refer...
  4. S

    Growing Oxide Layers in electrostatic fields

    Can an electrostatic field be used to create an oxide layer that has a permanent electric field? For a specific example; an aluminium domed van de graaff generator with no oxide layer. If it is turned on and allowed to contact oxygen, would the oxide layer store a permanent electric field?
  5. Isomorphism

    Why Does Charge Density Increase at Pointed Ends?

    1. Homework Statement : Homework Equations :[/B] A conductor is an equipotential surface. The charge density near a conductor is proportional to the electric field. Electric field is the negative gradient of potential and thus electric field is in a direction normal to the surface.The Attempt...
  6. Narayanan KR

    Will capacitors react to external electric field

    1. Passage of current via coil creates magnetic field (fig a), similarly external magnetic field linked to coil when changed created electric current in the circuit connected ( Faraday's em induction fig b). 2. Charging of capacitor using voltage source creates electric field in the capacitor...
  7. P

    Calculating magnitude of electric field at center of square

    Homework Statement Find the magnitude and direction of net electric field at the center of the square array of charges. Find E_x and E_y The square array of charges http://postimg.org/image/4gf94ymmf/ The Attempt at a Solution [/B] My attempt at drawing in the force vectors...
  8. O

    Help regarding intuition on particle accelerators

    I realize there have been multiple threads on this and believe me I tried my hardest to find these answers from them and other resources. Questions: 1) Is the van de graaff generator a particle collider? I am under the impression that it is meant to follow up on the Cockroft-Walton accelerator...
  9. KiNGGeexD

    Electrostatic fields- What defines an electrostatic field?

    I have a question about electrostatic fields! I was given these two equationsE= k [xy xˆ + 2yz yˆ + 3xz zˆ] E= k[y^2 xˆ+ (2xy+ z^2)+ 2yzzˆ] And asked to determine if either could be an electrostatic field, I'm not asking how to solve this problem but I'm not sure what defines an...
  10. C

    N??Solving Electrostatic Fields Problems

    Homework Statement A single isolated proton is fixed on a surface. Where must another proton be located in relation to the first in order that the electrostatic force of repulsion would just support its weight? 2)Two identical objects have charges from +6.0*10^-6 and -2.0*10^-6...
  11. L

    Simple electrostatic fields questions

    Imagine nine vertical and parallel lines drawn side by side. They represent infinite planes of uniform voltage. The first line has 0 V. The 2nd line has 1 V. The 3rd has 2 V and so on, with the 9th line having 8 V. The distance between each line is 1 cm, which is 0.01 meter. There is an...
  12. S

    Electrostatic fields in vacuum

    Homework Statement An atom H has a charge +q (=proton) and -q(=electron). q = 1,6.10^-19. The electron is circeling around the proton at r distance r = 0,53.10^-10m. What is the force as a result of the electrostatic interaction between the proton and electron Homework Equations...
  13. C

    Are there Electrostatic Fields at infinity?

    Homework Statement In the region x ≥ 0 there is an electrostatic potential V(x)=xexp(-λx) where λ>0 What is the electrostatic field at x→∞ Homework Equations The Attempt at a Solution My understanding is there is no fields at infinity because there is no electrostatic potential...
  14. B

    Calculating Forces in Electrostatic Fields w/ q & 4q

    Hello i have a problem that i need help with. Two fixed charges 'q' and '4q' are positioned along an axis with a separation d=5cm a) Calculate the forces acting on each charge Attempt - I understand that the the force eqn is F = qE - I also understand that i need to work out the...
  15. M

    The 3rd law of Newton with electrostatic fields

    Well, say there is an positive particle, and a negative particle. Newton said one is pulling the other, and thus it is pulling back. But we now know both particle actually creating fields, and the fields actually exerting the force on the other particle. so basically, this is not action...
  16. D

    Electrostatic Fields inside Charged Conductors

    Hi, I'm having a little trouble understanding why the field inside a charged conductor must be zero. I understand that when the charge is put on the conductor, they spread out to the surface such that the surface becomes an equipotential. But why does that mean the field inside must be zero?
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