# What is Electrical field: Definition and 58 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. ### Induced Electrical Field (Maxwell-Faraday's Law)

As we know that the magnetic induction causes an electric current in a wire and Faraday has formulated his Electromotive equation ##\epsilon=-\frac{d\Phi}{dt}##. And then Maxwell-Faraday's equation is: ##\nabla \times E=-\frac{\partial B}{\partial t}##, until now this was just an introduction...

3. ### Characterizing Total Charge of Conductor A in an External Electrical Field

Assume that a certain charge distribution ##\rho## generates an electrical field ##E_{ext}## in the surrounding space. We also note the corresponding generated potential ##V_{ext}##. Assume furthermore that a conductor A, with a definite shape and volume, is placed in field ##E_{ext}##, and is...
4. ### Electrical field outside a hollow spherical conductor

Hello everyone, There is an electrical field inside and outside (at the same time) the spherical hollow conductor when we place positive or negative charge inside, isn't it? I know this is because of the induced charges on the inner and outer surfaces of the conductor. There is no field inside...
5. ### Floating potential of a conductor in an electrical field

I'm interested in the following general question: Assume x,y,z is an axes system, and that the y-z plane is occupied by a conductive plate at a known potential V with respect to the earth. Now, a conductive material M of neutral global electrical charge is placed at some distance of the plate...
6. ### Electrical field near infinite, charged rod

Homework Statement Calculate the electric field at point ##P## if the distance from the center of an infinitely long, charged rod to point ##P## is ##a = 0.6m##; the charge density equals ##\lambda = -CX^2##, ##C=10^{-3}C/m^3##. Show all steps in finding the equation of the field, then find the...
7. ### Solve Proton Homework: Min Speed to Miss Lower Plate

Homework Statement In the figure, a proton, mass 1.67×10^−27 kg, is projected horizontally midway between two parallel plates that are separated by 0.20cm, with an electrical field with magnitude 7.8×10^5N/C between the plates. If the plates are 5.40cm long, find the minimum speed of the proton...
8. ### How to calculate the electrical field of planets?

All, I am not sure if this is the right forum for this but I believe it is the closest to the question I would like an answer to. I would like to calculate the electrical force between Mars and the Earth. I believe I understand that in order to do this, I must apply Coulomb's law: E=...
9. ### What is Electrical Field in a Closed surface with no charge

As per the Gauss Law , Net Flux Electric Field through a closed Surface (Gaussian Surface) is zero if no charge is enclosed. As per the definition of the Electrical Flux = Electrical Field Intensity dot product Area Vector i.e. Closed Integral of E.S If Electrical Flux is zero then as per the...
10. ### Does Applying an Electrical Field to One Side of a Conductor Double the EMF?

Assume a conductor in a rectangle shape for simplicity. Now, if I only choose one side of this rectangle, and apply external electrical field ∑ only to it, what EMF would I create on the conductor? I would simply say ∑, however then I had the following idea, and I started to doubt if I create...
11. ### Finding magnitude of electrical field at specific point

Homework Statement [/B] Two point-like charges are placed as shown in the figure, r1 = 28.0 cm and r2 = 56.0 cm. Find the magnitude of the electric field at point (p) shown in the figure. Let q1 = −13.0 µC, q2 = +30.0 µC. Homework Equations [/B] E1 = k*q1 / r^2 3. The Attempt at a...
12. ### How does a magnetic field affect an electrical field

More specifically, what happens and why when a magnet is brought close to a nonferrous charged object.
13. ### Interested in going into Electrical field (highschool student)

Going to Electrical field..(high school student) I recently began applying to colleges. I am planning on attending a 2 year community college first, but the college only offers electrical engineering technology so I had a few questions. 1. What is the difference between Electrical Engineering...
14. ### Electrical Field around Spherical Ball at origin

Homework Statement Spherical Ball centered at origin uniform ##\rho## with a radius a. Find E along x-axis. Homework Equations ##E = \frac{\rho}{4\pi\epsilon_0}\int\int\int\frac{r^2*sin\theta}{r_\rho^2} d\phi d\theta dr## The Attempt at a Solution Evaluate E spherically along the...
15. ### Discontinuity in electrical field.

Hi, Homework Statement I'd like to find the electrical field at the center of a hole made in a hollow sphere of radius R0 with uniform charge density σ. The radius of the disc-shaped hole is a << R0. Homework Equations I know that the electrical field of the sphere is Q/r2 for r>R and 0 for...
16. ### Effect of electrical field on annealing of thin film bismuth

I have been reading recently on the properties of evaporated thin film bismuth, particularly grain size and resistivity. Usually evaporated bismuth is amorphous and semimetallic, with very small grain size. Grain size can be increased and resistance lowered by annealing the film. It has been...
17. ### Semiconductor Electrical Field?

Homework Statement The electron concentration in silicon at T = 300K is: n(x) = 1016e(-x/18) cm-3 where x is measured in μm and is limited to 0 ≤ x ≤ 25. The electron diffusion coefficient, Dn = 25 cm2/s and the electron mobility is μn = 960cm2/Vs. The total electron current density is...
18. ### Creating an Electrical field equation

Homework Statement I have to find a general equation to find the magnitude of the resultant electrical field vector on a positive test charge by two charges of the same magnitude but opposite signs. The two charges are equidistant from the y-axis and are on the x-axis. Q1= positive charge Q2=...
19. ### Electrical field strength problem

I have completed the force column in the table however I am not sure what the question is asking me for the field strength calculation. am i to use the 25μC charge or the 8μC charge in the formula 1/4∏ε x Q/r^2, this may be obvious to someone with more experience of these questions, Thanks
20. ### Electrical Capacitator and Electrical Field question. Please help

So the problem is "An electric field of 7.85*10^5 V/m is desired between two parallel plates, each of area 38.0 cm^2 and separated by 2.45 mm of air. What charge must be on each plate?" Relevant equations: V=-E*d, C= (E0*A)/d, C=Q/V I have calculated the voltage by taking...
21. ### Double barrier potential in electrical field with matlab

Hello there :), I have a problem in calculating transmission probability through double barrier potential in electrical field with matlab. While doing some exercises form http://www.nextnano.de/nextnano3/tutorial/1Dtutorial_Transmission_NEGF.htm, I came to the last one, where external field is...
22. ### Electrical Field between plate

Problem: Two square metal plates are placed parallel to each other, separated by a distance d= 1.56 cm. The plates have sides of length L = 0.560 m. One of the plates has charge Q= + 1.74×10-6 C, while the other plate has charge -Q. Calculate the magnitude of the electric field between the...
23. ### Uniform electrical field - why?

In a uniform electrical field, why does the field strength remain constant? For a field where two metal plates, one negatively charged the other positively charged, why will E, electric field strength, always remain constant? If we assume the distance between two plates A & B, where A has a...
24. ### Effect of electrical field on heat capacity

Homework Statement Given the perfect gas molecules with permanent electrical dipole moment u in the field \epsilon. The potential energy is U = -u\epsilon\cos\Theta Derive the additional effect of \epsilon on the heat capacity. I need some hints, please help. Thanks.
25. ### Particle acceleration in electrical field

Homework Statement A charge is placed on the x-axis (q=+7.00 \muC, x=0.600 m), and another charge is placed on the y-axis (q=+9.00 \muC, x=0.400 m). A third charge (q=-6.00 \muC, m= 5.00 x 10^{-8} kg) is placed at the coordinate origin. If the charge at the origin were free to move, what would...
26. ### Calculating Electric Field from Force on a Charge

Homework Statement A 4C charge experiences 45i of force. What is the electric field at the charge? Homework Equations F=qE --> E=F/q The Attempt at a Solution Q=4 F=45i 0j I don't really know how to find the actual force from this component without an angle or anything...
27. ### Electrical field of an equialateral triangle

Homework Statement An equilateral triangle is formed with 3 rods, each with a length of 10cm. Two of them carry a charge of +63nC and 1 carries a charge of -63nC. The charge is uniformly distributed along each rod. What is the magnitude of the electric field at the center of the triangle...
28. ### Find the electrical field of a Spherical Shell

Homework Statement Consider a thin spherical shell of radius 14.0 cm with a total charge of 32.0 %C distributed uniformly on its surface. Find the electric field (a) 10.0 cm and (b) 20.0 cm from the center of the charge distribution. Homework Equations The Attempt at a Solution...
29. ### Equipotentials and electrical field

Homework Statement Just a quick question. The electrical field is stronger where the voltage is higher right? Or does it have to do with how close together the equipotential lines are?
30. ### Electrical field lines in conductive wire

Hi we connect a Voltage to heads of a conductive wire how will be the field lines inside Wire ? (cylinder wire) E = \rho J so ? :D field lines are parrarell inside wire ? in whole wire Electrical field is constant ? (J must be more in center of wire) what about Extreme...
31. ### Plot the graph of the electrical field

Graph Help! Plot the graph of the electrical field created by a point charge of 10^-6 C as a funtion of distance to the charge. Plot the graph for the range of the distances from 0.1m to 1m Should I use this equation... E= Q/(4.pi.e)x(d^2) as this is for electric field strength and not...
32. ### Review of Electrical Field Calculations

Hello, I have an assignment in my Electricity and Magnetism course that covers the last few chapters dealing with calculating charge, using Gauss's Law, and electric potential. I'm going through them right now, but physics isn't completely my strong point so I would really appreciate it if I...
33. ### How Do You Calculate Electrical Field Strength in Kapton Insulated Cables?

Dear All, How do i calculate the Electrical field strength in v/mm for a Kapton Insulated Cable. Conductor AWG 24/19 - 0,6 mm Kapton wall thickness : 1,0 mm Voltage : 15 KV Thanks.
34. ### Electrical Field of a Charged set of Spheres

Homework Statement Two spherical shells have a common center. A -1.37 x 10-6 C charge is spread uniformly over the inner shell, which has a radius of 0.0422 m. A +5.86 x 10-6 C charge is spread uniformly over the outer shell, which has a radius of 1.60 m. Find the magnitude of the electric...
35. ### What are the image charges inside the spheres?

Hi together I want to calculate an electrical field between a sphere and a plate, where the sphere has a certain voltage and the plate is on ground. Has someone a suggestion to begin?
36. ### Electrical Field Theory and Tension In A String

Homework Statement A ping-pong ball of mass 3.0 \times 10^{-15} is hanging from a light thread 1.0 m long, between two vertical parallel plates 10 cm apart, as shown. When the potential difference across the plates is 420 V, the ball comes to equilibrium 1.0 cm to one side of its original...
37. ### Electrical field outside spherical shell

Homework Statement An insulated spherical shell with its center in the origin and radius R has a surface charge density of \sigma(\theta)=\sigma_0\sin(\theta) when \theta is the angle from the z axis. Calculate the electrical field outside the shell at point z=R. Homework Equations...
38. ### Spring in an electrical field

1. Homework Statement A rigid rod of mass m and length l is suspended from two identical springs of negligible mass such that one spring is attached at either end of the rod. The upper ends of the springs are fixed in place and the springs stretch a distance d under the weight of the suspended...
39. ### Questions about Electrical Field and Magnetic Field

Hi there, I'm new to this forum and currently in year 11 Well, today I just got a worksheet in Physics lesson about nuclear radiations, stuff like alpha, beta and gamma rays... I pretty much understand most of what it was about until this "Right Hand Palm Rule" came up to me in the paper...
40. ### Electric Field Between +2 and -3 Charges

hi everybody, Homework Statement A +2 C charge is 20cm to the right of a -3 charge. What is the electric field on the line excatly halfway between the two charges? Homework Equations E = kq/d^2 The Attempt at a Solution force of attraction; therefore vector of -3 charge would...
41. ### Understanding the Electrical Field Lines of a Charged Insulating Disk

Homework Statement Sketch the electrical field lines of a uniformly charged insulating disk. Show field lines close and far away. Homework Equations none, conceptual The Attempt at a Solution For close to the surface of disk near the center the field lines are almost perpendicular...
42. ### What is the electric field at a distance of 2.0 m from a point charge of 40 J/C?

Homework Statement at a distance of 1.0 m from a point charge, the electric field is 40 J/C. What is the electric field at a distance of 2.0 m from the point charge? The Attempt at a Solution so, i understand that the elecric field should be = charge/distance(squared). so I did...
43. ### Electromagnetism II - Potential and Electrical Field of a Spherical Shell

Homework Statement Consider a thin spherical shell having surface charge density σ, and radius a as shown in the diagram (see attachment). Find, by integration over the sphere, the potential at a point P, a distance r fromthe centre of the sphere, for r > a. Using this result also find...
44. ### Another Electrical Field Question

A test Charge of +1.0x10^-6 C is 40cm from a charged sphere of 3.2x10^-3 C. a)how much work was required to move it there from a point 1.0x10^2m away from the sphere b)how many electrons were gained or lost from the test object to create the charge? Given: q1 = 1.0x10^-6 C q2 =...
45. ### Calculating Electric Field Strength from a Point Charge

You are observing the effects of a single point charge with a magnitude of +4.3 mu Columbs calculate the strength of the electric field 3cmaway from the charge in any direction.. first i don't know why there is mu C, shouldn't it have been something like 4.3 x10^-7 C? or does mu represent...
46. ### Simple electrical field problem

A metal sphere of radius R with a charge q is surrounded by a concentric metal sphere as shown in Figure P.23. The outer surface of the the sperical shell has a charge of + 30.0*10^-6C and the inner surface of the shell has a charge of +25.0*10^-6C. (a) Find q (b) Sketch qualitative graphs...
47. ### Adding electrical field vectors

I have this standard homework problem to find the electrical field at a point. I figured out most of the math like the x and y components of the E Field from the two charges acting on the point. I also have the correct answer and i don't understand why the x components of the electrical charge...
48. ### Electrical field at the center of a hemisphere

Charge is distributed uniformly on the surface of a hemisphere. Find the electrical field at the center of the sphere due to that. Can anyone help me?pls ^___^
49. ### Finding the Electrical Field from the Electric Potential

I am trying to solve this problem: The electric potential in a region of space is V = 210x^2 - 270y^2, where x and y are in meters. Find the E-field at (3m, 1m) So I started with: E = \frac{V}{d} so then I plugged x and y into the electric potential equation and got V= -200 Volts...
50. ### Quick question reguarding electrical field lines.

Can anyone answer me a curious question. Why are electric field lines perpendicular to equipotential lines? Is it because force and charge are inversly proportional or is there a more simple reason? Thanks.