What is Electric field strength: Definition and 135 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. R

    What is the electric field strength?

    Homework Statement 50 pJ of energy is stored in a 2.0 cm*2.0 cm*2.0 cm region of uniform electric field. What is the electric field strength? Homework Equations not sure The Attempt at a Solution not sure how to start this problem
  2. C

    Finding magnitude of electric field strength

    Homework Statement Consider three charges arranged as shown. What is the magnitude of the electric field strength at a point 2.7 cm to the left of the middle charge? The value of the Coulomb constant is 8.98755 × 109 N · m2/C2 . Answer in units of N/C. Homework Equations I'm truly...
  3. A

    Two spheres, solve for electric field strength

    Homework Statement Two 2.0-cm-diameter insulating spheres have a 6.50 cm space between them. One sphere is charged to + 89.0 nC, the other to - 95.0 nC. What is the electric field strength at the midpoint between the two spheres? Homework Equations Esphere = KQ/r^2 k = 8.99 * 10^9...
  4. F

    Find the electric field strength inside a solid sphere.

    Homework Statement A solid sphere 25cm in radius carries 14uC, distributed uniformly throughout its volume. Find the electric field strength (a.) 15cm, (b.) 25cm, (c.) 50cm from the sphere's center. R = .25m Q = 14 * 10^-6 C Homework Equations p = q/(volume) E = (kq)/r^2 The...
  5. N

    Defining Flux in the Context of Electric Fields

    A 124 cm diameter loop is rotated in a uniform electric field until the position of the maximum electric flux is found. The flux in this position is measured to be 6.33 x 105. What is the electric field strength?
  6. S

    Calculate the electric field strength and the direction on the z-axis resultant

    Homework Statement Calculate the electric field strength and the direction on the z-axis resultant from 3 line charges of blah blah and blah located at (x,y), (x1,y1), (x2,y2) respectively. Homework Equations I assume I just use E = k.Q/r^2 The Attempt at a Solution So I work out...
  7. J

    Electric field strength of wire problem

    The electric field strength 5 cm from a very long charged wire is 2000N/C . What is the field strength 10 cm from wire. A)1x10^-4 N/C B)1x10^3 N/C C)9.9x10^7 N/C D) None of these I have E=kq/r^2 and infinite line charge E=(2k\lambda)/R 2000 * .05 m^2 /K =q q=5.56 E-8 k5.56E-8/.^21 m =...
  8. Z

    Electric field strength and potential gradient

    A bit of a problem. My book teaches me that E = -(dV/dx), where E is the electric field strength, V is the electric potential, and x represents displacement. But, it also suggests along with the above formula that E = -(V/d) and displays a circuit with a battery of p.d. V and two parallel...
  9. N

    What is the equation for calculating electric field strength between two plates?

    Homework Statement Two plates each have an area of 80cm2 and are placed facing one another in a vacuum. If the top plate carries a positive charge of 25nC and the bottom plate carrie, a charge of -25nC. Find the electric field strength between them. Permitivity of free space = 8.9 * 10^-12...
  10. S

    Charge vs. Electric Field Strength

    The question in question: "If charge was plotted versus electric field strength; what shape of graph would you get? How would you straighten in? What quantity would the slope of the straightened graph represent?" Related equation: |E|= F/q Ignoring the graphing information, the question...
  11. B

    Electric Field Strength charges

    Homework Statement Charge A has 10 electric field lines coming out, Charge B has 20 lines coming out, and Charge C has 30 lines coming in. Which pair of these charges will have the largest force between them if placed one cm apart? Homework Equations The Attempt at a Solution Is...
  12. A

    Electric field strength from a light bulb

    Homework Statement What is the approximate electric field strength of the electromagnetic waves radiated by a 100-W light bulb, measured 3.0m from the bulb? Homework Equations $$\vec{E}=\frac{kq}{d^{2}}$$ $$P=\frac{2kq^{2}a^{2}}{3c^{3}}$$ The Attempt at a Solution I solved for...
  13. J

    Calculating Electric Field Strength between Charges

    Homework Statement q=4.0x10^-6C, 8.0x10^-6C d=2m Homework Equations Two charges of +4.0x10^-6 C and +8.0x10^-6C are placed 2.0m apart. What is the field strength halfway between them? The Attempt at a Solution netEa= (9.0x10^9)(4.0x10^-6C) + (9.0x10^9)(8.0x10^-6C)...
  14. M

    Electric field strength and speed

    The electric field strength is 1.70×104 inside a parallel-plate capacitor with a 1.40 spacing. An electron is released from rest at the negative plate. What is the electron's speed when it reaches the positive plate? Help please...
  15. C

    What electric field strength will cause the bead to hang suspended in the air?

    1. A 0.180g plastic bead is charged by the addition of 0.700 x 10^10 excess electrons. What electric field strength will cause the bead to hang suspended in the air? 2. Is amount of excess electrons the exact same as the charge of the bead?? 3. I am sure you use F=qE. But I am...
  16. M

    Calculating Electric Field Strength to Stop an Electron

    Homework Statement An electron moving to the right at 3% the speed of light enters a uniform electric field parallel to its direction of motion. The electron is to be brought to rest in the space of 6.0cm. What is the strength of the field?______N/C Homework Equations F = q * E The...
  17. L

    What Does the Slope Represent in a Voltage vs. Distance Graph?

    Well I have this lab on electric field lab and what I did was measure the voltage from different distances on a parallel plate. So when I plotted the graph Voltae vs. Distance, I got a linear line and the equation was y = 85x (somewhat like that disregarding the y-intercept). My concern is what...
  18. P

    Electric Field Strength at Point Z

    what are the magnitude and direction of the electrical field strength at point Z in the situation below? negatively charged sphere, x(-2.0*10-5C) is left most, 60 cm to the right of it is a positively charged sphere,Y (8.0*10-6C). Point Z is 30 cm to the right of Y. What I did: First i...
  19. P

    Electric Field Strength from point charges

    Question Charges at three corners of a square are shown in Figure P26.34, in which n = 9. To answer the following questions, use the letters k, Q, q, L, and m. IMAGE IS LOCATED HERE: http://www.webassign.net/knight/p26-34.gif a) Write the electric field at point P in component form. b)A...
  20. R

    Initial electric field strength

    Homework Statement The initial electric field strength between oppositely charged parallel plates is 3.0 X 10^3 N/C, what would the electric field strength become if half of the charge were removed from each plate and the separation of the plates were changed from 12 mm to 8 mm? Homework...
  21. M

    What is the electric field strength at the center of the triangle?

    Homework Statement What is the electric field strength at the center of the triangle? Three 13.0 -cm-long rods form an equilateral triangle. Two of the rods are charged to + 19.0 nC, the third to - 19.0 nC . What is the electric field strength at the center of the triangle...
  22. C

    Confused about electric field strength and PE

    I have just started to learn these things(electric field strength, electric potnential energy and electric potential). I am not very clear about what they are. I would like to ask a few questions here. Why is electric field strength somtimes +ve but sometimes -ve? what does each of them...
  23. U

    Electric Field Strength H Units - Ampere Turns/Meter?

    What are the units of the electric field strength H? I know that H = NI/L for a solenoid and I'm wondering if there is any condensed unit or if it is just ampere turns per meter.
  24. A

    Electric field strength in a square.

    Hi guys, Suppose I have a point O in the centre of the square (of side length X), where the top 2 corners of the square carries a positive charge each and the bottom left corner a negative charge and the bottom right corner a positive charge, what would the magnitude and direction of the...
  25. D

    Calculating Electric field strength

    Alright everyone, normally I am prett good with electrostatics, butlately...I've been in a serious rut. My physics professor has asked us to varify the electric field at a distance r from a cylindrical gaussian surface, under three conditions. 1) with a constant chrage density, 2) with a...
  26. C

    Electric field strength problem

    Here is my solution. I completed this problem to the best of my ability and I am asking for someone to check and correct my solution if possible. I am not sure if my answers are correct, although and my thinking might also be flawed :confused: q1= 6.0e-6C q2= 1.5e-6C q3=-2.0e-6C The...
  27. Y

    Electric Potential and Electric Field Strength

    Hey! I've got my A-Level Physics exam on Thursday, and I'm just doing some past papers and I'm totally confused! Please help! One of the questions (multiple choice) was saying which statement was incorrect. The answer was: Electric potential is zero whenever electric field strength is...
  28. F

    Electric field strength (should be easy)

    What is the electric field strength in a region where the flux through a: 1.0cm \times 1.0cm flat surface is: 65N\frac{m^2}{C}, if the field is uniform and the surface is at right angles to the field? [] []----> E [] Since the field points at a right angle to the surface we have a norm...
  29. D

    Electric Field Strength Question

    I need help with the following question. A diopole is made up of two charges, Q1 and Q2, that are separated by a distance of 1 meter. Q1 has a charge of +3C and Q2 has a charge of -3C. What is the electric field strength of the field set up by these two charges at a point exactly halfway...
  30. J

    The Electric Field Strength of a Proton Accelerated at 1 Million g

    What is the electric field strength at a point in space where a proton experiences an acceleration of 1 million "g"? I'm completely lost on this one I know it's bound to be something simple but I just can't figure out where to start with it, well other than that 1 million "g" should be...
  31. M

    Explain why the electric field strength is zero

    I am stuck on my physics homework. I can manage the latter question, how ever when i work out the first one my working out has no rhyme nor reason (nor a right answer). Any help will be great. A small metal sphere on an insulating rod is placed on a top pan balance, as shown in the diagram...
  32. S

    Electric field strength due to two point charges

    Given are two charges +1 X 10^-6 and one 3 X 10 ^ -6 distnace of 10 cm apart I know there is a poitn in between these two and it is 4 cm from the 1.0 X 10^-6 charge But i am asked to plot the elctric field strength as a function if the elctric field is pointing right, then positive...
  33. E

    Calculating Electric Field Strength from Kinetic Energy and Displacement

    Here's the problem: A particle with a charge of 4.4nC is in a uniform electric field E directed to the left. It is released from rest and moves to the left. After it has moved 6.00 cm, its kinetic energy is found to be 3E-6 Joules. a) What work was done by the electric force? .000003 J b)...
  34. M

    What is the electric field strength

    Problem 16. Three charges: +8.2uC 4.8 cm to the left of 4uC and a -2.3uC 2.1 cm to the right of the 4uC charge. What is the electric field strength at a point 2.7cm to the left of the middle charge? In N/C. Note" Is the answer 1.733218664*10^7 from the 8.99*10^9...
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