What is Electric field lines: Definition and 85 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. S

    Which, if any, of the following statements about electric field lines is/are true?

    Which, if any, of the following statements about electric field lines is/are true? The electric field is always perpendicular to the surface outside of a conductor. - TRUE It is not possible for the electric field to ever be zero. - FALSE It is possible for two electric field lines to...
  2. Drakkith

    Interaction Between Magnetic and Electric Field Lines

    Hey all. I was wondering what the interaction between Electric and Magnetic field lines are. For example, when you hold up a magnet against a charged electrode. I tried searching in google, but everything just turned up one or the other or how a moving charge makes a magnetic field and etc.
  3. J

    Electric Field Lines and Equipotential Contours

    Homework Statement The adjacent figure shows the E-field lines (with arrows) and equipotential contours for a certain charge configuration. Determine for each of the following statements whether it is true or false. Assuming that these contours are those of a point charge at the origin...
  4. S

    Why are electric field lines straight around electrons moving at relativistic speed?

    Imagine an electron in uniform motion moving at a speed near the speed of light. Pictures I've seen of the electric field around such a charge look like this one from wikipedia: The field lines are straight, but clustering around the plane perpendicular to the direction of motion...
  5. A

    Induced Electric Field Lines When a Magnetic Field Crosses a Plane

    If a time varying magnetic field of infinite dimensions crosses a plane at right angles what can we expect induced electric field lines to look like? Straight lines with direction determined by the right hand rule?
  6. P

    Calculate R from Electric field lines.

    1. The problem statement The electric field E (arrows) is produced by a point charge. Find R in meters Homework Equations E(due to pt charge) = kq/R^2 # of field lines/unit area represents relative field strength (only statement in my notes that seems to apply to problem) The...
  7. M

    Propgating Electric Field Lines

    Hi, I am trying to get a better idea of how E-field line diagrams are drawn. The following link appears to be a nice example of field lines associated with a single charge moving linearly with constant velocity [v=0.5c]. By default, after pressing go, the animation displays the field lines for...
  8. D

    Electric Field Lines, Misconception

    Homework Statement This is a question I read in an article that discusses about misconception of physics among students. they only provided the question and some of the wrong principles students suggested. Three Points , located on the vertices(vertexes) of an equilateral triangle and have...
  9. E

    Direction of electric field lines

    I have an intuitive understanding of electric fields but when it comes to defining it on a test I wouldn't know what to say. Is the electric field defined as the force produced by a charged object on a positive test charge or any other charged object? Also if you were told to draw the electric...
  10. L

    Understanding Equipotential Lines and Electric Field Lines

    I understand the concept of electric field lines but don't understand the interaction with the equipotential lines. I understand that along each equipotential line/surface that there is no change in potential energy. I also understand the field lines need to cross perpendicularly with the...
  11. R

    Uniformly distributed electric field lines

    Homework Statement A positive charge is placed in the center of a cube. Are the intersections of the field lines with a side of the box uniformly distributed across that side. Explain. === I have missed some lectures due to getting the swine flu (ugh) and the material is not exactly...
  12. G

    Electric field lines questions

    Homework Statement The electric field from two charges in the plane of the paper is represented by the dashed lines and arrows below. Select a response for each statement below. (Use 'North' towards top of page, and 'East' to the right) The force on a (-) test charge at N is directed...
  13. J

    Oscillating Electric Field Lines

    I'm have some conceptual problems with electric fields and waves. When I think of electromagnetic waves I imagine field lines emanating from a charge that is oscillating, consequently causing the field lines to oscillate. In diagrams showing field lines, the electric field runs parallel with the...
  14. B

    Angle made by electric field lines

    Homework Statement an electric field line emerges from a positive point charge +q1 at an angle x to the straight line joining it to a negative charge -q2.at what angle y will the field line enter the charge -q2? Homework Equations The Attempt at a Solution sin(y/2)=sin(x/2)(q1/q2)^1/2
  15. W

    Magnetic monopoles, electric field lines and equipotential surfaces

    Homework Statement (i) Explain why it would not be possible to write the magnetic Field (B-field) in terms of a vector potential (A) IF magnetic monopoles existed. (ii) For an electrostatic field (E-field), define the electrostatic potential (Fi), and explain CONCISELY what is meant by a...
  16. J

    Understanding Electric Field Lines: Curving and Splitting Nodes

    Homework Statement Hey I'm supposed to draw electric fields for this problem and I can't figure these 2 out. Homework Equations There really isn't any. The Attempt at a Solution It's included in the picture http://img135.imageshack.us/my.php?image=physicsge1.jpg
  17. J

    Drawing Electric Field Lines and Equipotential Lines

    Homework Statement You have two metal electrodes, not touching each other. One is a circle and one is like a thin plank. The plank is at a lower electric potential. Draw electric field lines between them, including direction. Draw equipotential lines in the space between the electrodes...
  18. D

    Sketching Electric Field Lines of Circular Arc w/ Uniform Charge

    Homework Statement Sketch a field line picture for a circular arc with a uniform linear charge density. Homework Equations The Attempt at a Solution To do this do I just break up each segment on the arc into small segments each of charge dQ and draw the field line along the...
  19. K

    Defibrillator and electric field lines

    I am asked to draw a picture of a person 1 second before patient is defibrillated and 10 seconds after a patient is defibrillated. I am asked to draw a general picutre of the electric field lines and charges at these two points. I know that the goal of defibrillation is to enterfere with the...
  20. S

    Electric field lines in a dielectric_ figure attached in ee thread

    Hi all, I am trying to solve numerically as well as model the electric field lines coming out of a electrode (not a point charge) in a dielectric medium. ANy suggestions would be greatly beneficial _________________________________________________ _ separated by d + separated by d _...
  21. S

    Help to solve electric field lines in a dielectric

    Hi all, I am trying to solve numerically as well as model the electric field lines coming out of a electrode (not a point charge) in a dielectric medium. ANy suggestions would be greatly beneficial _________________________________________________ _ separated by d...
  22. C

    Experiment with Electric field lines

    Homework Statement Hello all. I need help or ideas on making an experiment in which I need to show the electric field lines. I think it should be somewhat similar the the experiment when you put lots of little metal pieces on a piece of paper and then you put a magnet below the paper, and...
  23. C

    Magnetic and Electric Field Lines

    Homework Statement Magnetic and electric field lines are visually defined by field lines. Give three points to explain how the field lines can be used to describe the characteristics of these fields. Homework Equations (Not sure if needed to describe) Fm = qvBsin0, Fm = IlBsin0 The...
  24. J

    What can we determine about the electric field lines from two charges Q1 and Q2?

    Hello Everyone! i need some guide and hints about this... Here is the link for the picture... From the figure, the electric Field lines arising from two charges Q1 and Q2 are shown. From this drawing we can see that A) The electric field could be zero at P2 B) Both Q1 and Q2 have the...
  25. A

    Sketching Electric Field Patterns for Charged Objects

    Homework Statement a) Sketch the electric field pattern setup by a postively charged hollow sphere. Include regions inside and regions outside the sphere. b) A conducting cube is given a positive charge. Sketch the electric field pattern both inside and outside the cube. The Attempt at a...
  26. A

    Examples of Electric Field Lines

    Does anyone know a good site where they show you examples of how to draw Electic Field lines? Problem relating to it: a) sketch the electirc field pattern set up by a positively charged hollow sphere.
  27. N

    Electric Field Lines: Symmetry between Opposite Charges

    I know that the electric field lines between two oppositely charged points are symmetric, but I can't seem tof ind any refrence as to when this symmetry breaks down. I want to say that electric field lines do not maintain symmetry if the two charges are not equal but opposite, e.g. a -4 and...
  28. iamhumble

    Windows Sofware To Graph Electric Field Lines ?

    Windows Sofware To Graph Electric Field Lines ?? Hi Everyone, Does anyone know of any Windows software out there that will graph electric field lines? I recently did a physics lab where I determine point charges of some "x-rays" and from the data I gathered I need to graph the electric...
  29. D

    Electric Field Lines and points

    Could anyone pls explain to me: what is the similar thing among points in the same Electric Field Line? (I have 2 particles A and B which are + and -, then I have 2 other ones C and D --> how can I know that C and D are lying in 1 EF line or in 2 different lines?) Thx so much.
  30. P

    Explaining the Relationship Between Electric Field and Equipotential Lines

    Why are electric field lines always crossing equipotential lines at right angles? Can somebody please explain this to me? Thanks :smile:
  31. P

    Electric Field Lines and right angles

    Why are electric field lines always crossing equipotential lines at right angles? Can somebody please explain this to me? Thanks :smile:
  32. zoobyshoe

    Electric & Magnetic Field Lines: Why Do They Bow Out?

    This site has a typical representation of the electric field lines between a negative and positive charge: Electric Field Lines Address:http://physics.bgsu.edu/~stoner/P202/efield/sld006.htm Although the lines emerge from one particle and converge on the other, they bow out in between...
  33. L

    Electric Field Lines: Special Theory of Relativity Paradox

    the concept of electric field lines are came into existence to satisfy the special theory of relativity which implies that action of electrostatic forces can not be instantaneous but takes some time to act on teh other charge i.e. if a charge produces an electric field then its effect will be...
  34. P

    Why must equipotential surfaces be perpendicular to electric field lines?

    Can anyone help me to understand why equipotential surfaces must always be perpendicular to the electric field lines that pass through them? My textbook gives what seems to be a simple mathematical explanation, but the logic is escaping me. It states that dV= -E.ds = 0, (where the "."...
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