What is Electric fields: Definition and 506 Discussions

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. G

    Electric Fields and Electric Potential

    Homework Statement An Electron enters a parallel plate apparatus that is 8cm long and 4cm wide. The electron has a horizontal speed of 6*10^7 m/s. The potential difference between the plates is 6*10^2 V. Calculate the electrons velocity as it leaves the plates. (ans. 6*10^7 m/s [E 3.3° N])...
  2. B

    How Does Gauss' Law Apply to Currents in Electric Fields and Circuitry?

    I am designing a device, which will utilize an electric field. The question I have run into is whether or not the current is treated as the charge enclosed for Gauss' Law, or if there's another way I would calculate it. Also, am I correct that the voltage of the circuit would be different than...
  3. B

    Electric Potential and Electric fields

    Homework Statement Can there be a point in space where there is an electric potential but not electric field? Can there be a point in space where there is an electric field but no electric potential? Explain you answer. What would the electric field lines look like if the electric field was...
  4. ExplosivePete

    Discontinuous electric fields

    Griffiths introduction to electrodynamics talks about how electric potential is always continuous and electric fields are continuous except in the case of a surface charge density. This seems fair assuming you can have a continuous surface charge Density, but in the real world, these densities...
  5. Azura

    About electric fields (Symmetry)

    1) Imagine you have a clock but in each number you have a charge "q". If I have a test charge Q at the center, then by simetry, the net force on Q is zero. I imagined like, 1 cancels 7, 2 cancels 8, etc... But then, if I have a polygon with 13 sides, with a test charge Q, the net force also...
  6. R

    Electric Fields Question, What is the speed of the electron?

    Homework Statement An electron is released from rest in a weak electric field given by -2.8 x 10^-10 N/C [PLAIN]https://www.flipitphysics.com/Content/smartPhysics/Media/Images/Tipler/Symbols/jhatbold.gif. After the electron has traveled a vertical distance of 1.9 µm, what is its speed? (Do not...
  7. jlmccart03

    Electric field strength near a metal plate

    Homework Statement A total charge of 21 μC is applied to a thin, 1μm square metal plate 72 cm on a side. Find the electric field strength near the plate's surface, far from the edges. Homework Equations I think E = kq/r^2, but I really don't know. The Attempt at a Solution I am...
  8. W

    Understanding Electric Fields and Flux in Charged Objects

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  9. E

    I Why can't atoms accept energy from static electric fields?

    Though I am definitely not an expert in any way in QM, I understand that on a basic level quantum systems can be solved using schrodinger's equation. For a hydrogen atom, the wave function of the electron is found by using the hydrogen proton as an external potential and proceeding from there...
  10. Schaus

    Electric fields - Finding Net force acting on Q2

    Homework Statement What is the Net force (include direction) acting on charge Q2 due to Q1 and q? (ans: Fnet = 174N right) Homework Equations F=kQ1Q2/r2 E=F/QThe Attempt at a Solution I've figured out a) and b). It's just c) that's giving me trouble. I tried using the first equation - (9.0 x...
  11. K

    Explaining Why Gas Conducts Electric Fields

    Homework Statement Explain why the gas becomes conducting only when the electric field in the tube reaches certain value? 2) why does fields does from higher potential to lower potential? Homework Equations F=QE The Attempt at a Solution If we increase the E then the Force will also increase...
  12. O

    How do electric fields create forces on particles?

    Alright, I feel this may be a pretty basic question, but I have not gotten a satisfying answer yet. I'm taking Electromagnetism right now and I got to thinking: how do fields physically interact? What I mean by this is, on a subatomic level, a field can create a force on another particle or...
  13. E

    Question about equipotential lines and electric fields

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  14. Quadrat

    Electron passing through a magnetic and an electric field

    Homework Statement An electron with velocity ##\vec{v}_0=8.7*10^4(m/s)## (in the î direction) passing through an area with a uniform magnetic field ##\vec{B}=0.80 T## (in the negative k̂ direction). There's also a uniform electric field in this area. What is the magnitude and direction of...
  15. I

    Does electric fields affect a compass

    By electitc field, i do not mean the magnetic field produced by a current carrying wire, but rather between charged particles. If a compass is placed between the electric field, will the compass needle delfect or will it just continue pointing in the initial direction?
  16. T

    Curvature of electric field around center of a quadrupole

    Hello all. I am working on a research project involving the Stark effect and its application in molecular guides and came across a bit of math in a paper that I don't understand. In this paper http://arxiv.org/abs/physics/0310046 there is an equation in the introduction concerning the electric...
  17. Ian Baughman

    Electric Fields (Uniformly Charged Plates)

    Homework Statement In the figure two large, thin metal plates are parallel and close to each other. On their inner faces, the plates have excess surface charge densities of opposite signs and magnitude 7.76 × 10-22 C/m2. What is the magnitude of the electric field at points (a) to the left of...
  18. G

    Question about Electric Fields and Charges

    Homework Statement So I was given some questions as practice, and I can't seem to do them. Here is a link to the questions: http://i.imgur.com/ZmkqCAV.jpg (the answers are in square brackets) Ive only been able to calculate Q3 and Q2 so far. I would really especially like help with Q1. I've...
  19. B

    Why does an electron shell further away from nucleus has higher energy?

    Using electrical potential energy =1/4πεo Q1Q2/r , a particle further away from nucleus has lower magnitude of energy Using coulomb's law, a particle further away from nucleus experiences weaker attraction, hence less energy is needed to maintain orbit* around that e-shell compared to a...
  20. S

    Questions about electric fields, voltage and electric energy

    1. If e.m.f is NOT a force, but actually energy – and e.m.f is measured in Voltage – then why is p.d. (V) NOT used up? Since we know energy *does* get used up by the component. I know the electrons are just the medium – energy carriers – but Voltage doesn’t mean number of electrons; it means...
  21. Adeel Ahmad

    Physics 2 Electric Fields, Circuits, Magnetism

    Can someone please help me out with this practice test and provide explanations?
  22. T

    Relation between magnetic and electric fields

    Homework Statement What is the electric field strength at the position of the proton in the figure?(Figure 1) Assume that B = 0.10 T and F = 3.4×10−13N . Figure 1: https://session.masteringphysics.com/problemAsset/1385081/6/35.P29.jpg Homework Equations Honestly I don't know. Since we have a...
  23. T

    A Charged Conductive Plate with a Charged Plane

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  24. S

    How are electric fields detected?

    How do you detect a very weak electric field? What kind of measurement devices are out there? What are the most sensitive devices used for measuring electric fields? I'm looking for something comparable to how SQUIDs or quartz resonators can be used to detect magnetic fields.
  25. J

    I What are magnetic and electric fields?

    I hesitate to ask this but what are electric and magnetic fields? We are told that the electromagnetic force is carried by the photon (which consists of oscillating electric and magnetic fields) but the photon does not cause (?) or interact with external magnetic and electic fields. Presumably...
  26. H

    Electric fields between parallel plates

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  27. kostoglotov

    How conductors/resistors affect electric fields?

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  28. T

    Understanding Electric Fields and Work Done to Move Charges

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  29. R

    Do zwitterions respond to electric fields?

    I know Zwitterions contain both a positive and negative charge. As such, I know that the zwitterions will not migrate towards either pole of the field. My question is: will the zwitterions align with the electric field lines?
  30. M

    Electric field between a needle and a plate

    http://i66.tinypic.com/2yts08m.jpg I was doing an experiment in which i have a needle perpendicular to a metal plate. I run 210kV between them. I want to find out the electric field between the two, and I also want to know the electric al field density throught the metal plate? Pls help. I...
  31. J

    Electric field from spherical charge distribution

    Hello. I have a problem calculating the electric field from spherical charge distribution. The exercise is: 1. Homework Statement Homework Equations To solve the problem for $$ 0\le R < a$$ i tried 2 ways: $$ \vec{E} = \frac{\vec{a_R}}{4\pi\epsilon_0}\int_v\frac{1} {R^2}\rho dv $$ and the...
  32. P

    Calculating Charge at the Center of a Spherical Shell has me stumped

    Edit: Forgot to type "stumped" at the end of the title 1. Homework Statement Instead of typing it out, a link to a scanned document of the problem is here: http://imgur.com/Be3jSLp. Homework Equations The equations to use are stated in the problem here: http://imgur.com/Be3jSLp The Attempt...
  33. kostoglotov

    How electric fields store energy in a capacitor

    Homework Statement The Question is here: imgur link: http://i.imgur.com/wIlUZMM.jpg Homework Equations U_c = \frac{\kappa \epsilon_0 A d E^2}{2} U_c = C \Delta V_c \kappa: dielectric constant \epsilon_0: permittivity of free space C: capacitance The Attempt at a Solution [/B] I...
  34. P

    Electric Fields in Coaxial Cables: Understanding Bound Charge Densities

    Homework Statement http://postimg.org/image/vzhqi8er5/ Homework EquationsThe Attempt at a Solution I understand all the calculations here - http://www.physicspages.com/2012/10/18/coaxial-cable-with-dielectric/ I have one issue that is bugging me though - if λ charge density is distributed over...
  35. O

    Question on conservative and non-conservative nature of electric fields.

    Hi all :) I am about to finish the chapter of electromagnetic induction in my class. And I taught my students that the electric field induced due to changing magnetic flux is different that the electrostatic field due to stationary charges(Now I am wondering would it be wrong if I used the...
  36. gracy

    Two electric fields perpendicular to each other -- how?

    Homework Statement four point charges are placed at the corners of a square as shown in the figure having side 10 cm.If q is 1μC then what will be electric field intensity at the centre of the square? Homework Equations 3. The Attempt at a Solution [/B] Half of diagonal a/√2 0.1/√2...
  37. R

    How would one describe the universe in which

    there are no electromagnetic waves? All I know is that there is a modified version of the Maxwell equations (in differential form) for such a universe, such as (the arrows represent vector arrows): →∇x →B = μ0 →j + μ0 ε0 ∂→B/∂t instead of having ∂E/dt in the last term (which would be the case...
  38. A

    Electric field generated by voltage on a sheet

    Hi All, I'm trying to calculate the electric field at a point above a sheet with the voltage V. The space above is filled with a dielectric with known bulk conductivity and relative permittivity. And the sheet is electrically isolated from the space. My major is not physics so thanks for your...
  39. M

    What is the electric field at point P?

    Homework Statement Point P is collinear with a +2.80 μC charged particle and a -8.50 μC charged particle as shown in the diagram below. Point P is 10 cm to the left of the positive charge and 20 cm to the left of the negative charge. What is the electric field at point P...
  40. M

    Electric fields, particles and deflection

    Homework Statement Explain the circumstances that enable a particle to move un-deflected with uniform motion through an electric field if it is given an initial velocity perpendicular to the electric field. Assume the electric field is the only field present.[/B] Homework EquationsThe Attempt...
  41. C

    Understanding the Fundamentals of Electric Fields....

    How does an electric charge produce an electric field? How is this field maintained over time without the input of energy? When the charge moves, why is or isn't there any remnant of the field left behind in space?
  42. Jimbob999

    Surface Charge Density (Electric Fields)

    A disk with a uniform positive surface charge density lies in the x-y plane, centered on the origin. The disk contains 2.5 x 10-6 C/m2 of charge, and is 7.5 cm in radius. What is the electric field at z = 15 cm? I have used the formula...
  43. goooogle

    Electric Fields problem: Can someone please check my work?

    "a +4nC charge is 6/0 cm along a horizontal line toward the right of a -3nC charged object. Determine the E field at a point 4.0 cm to the left of the negative charge." From what I understand, it goes Point ___ 4cm ____ (-3nC) _____ 6cm ____ (+4nC) Using that, I got the answer to be -14.75 nC...
  44. T

    Changes in electrostatic potential energy of a moving object

    Homework Statement "An object is moving in a straight line from a positively charged area (A) to a negatively charged area (B). Explain how the electrical force and electrostatic potential energy experienced by the object will vary when it is neutral (has no charge)." Homework Equations N/A as...
  45. R

    Electric fields and capacitors

    Hi guys, I was tutoring some students and I was explaining them how to calculate the capacitance between two parallels planes. They made me some questions and actually I am not quite sure about my answers! I started by showing them how to calculate the electric field generated by a single...
  46. 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...
  47. S

    Coulomb's Law and Electric Fields

    Examine the charge distribution shown: b) What is the net electric field acting on charge 1? Attempt at the answer: E2 = Kq2/r2^2 = (9.0 x 10^9 Nm^2/C^2)(3.0 x 10^-5 C) / 2.0m^2 E2 = 6.75 x 10^4 N/C E2 = E3 ( therefore, same procedure) eNet = Sqr.rt. 6.75 x 10^4 N/C^2 + 6.75 x 10^4 N/C^2...
  48. Shinwasha

    Struggling with a concept in regards to electric fields

    So I'm trying to figure out the electric field that is acting on a point. This point is .3 m right of a point charge with -2N/C and .8m from a point charge with +4N/C. I've drawn it out, and realize both will have an impact on this object. what the issue I'm having is figuring out a formula to...
  49. J

    Electric Fields and Charges Fill in the blanks

    Homework Statement [/B] Select the answers which complete the statements below (e.g., if answer A completes the first statement, and answer B the others, enter ABBBB). A) positive B) negative C) neutral D) cannot tell A positive point charge is brought near the outside surface of a...
  50. M

    Electron traveling between two plates. Electric Fields?

    Homework Statement An electron traveling horizontally east passes between two horizontal, oppositely charged plates and is deflected downward. Part A: Passing through the same space between the plates, in what direction (if any) a proton traveling horizontally east would be deflected? Part B...
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