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).
Homework Statement
The electric fields created by a point charge, a conducting sphere and insulator sphere are identical, if they all have the same amount of charge and the field is measured outside the spheres.
Homework Equations
The Attempt at a Solution
I think its...
Homework Statement
What are the magnitude and direction (in degrees counterclockwise from the horizontal) of the electric field at the center of the square of Fig. 23-31 if q = 0.9*10^-8 C and a = 5.1 cm?
http://personalpages.tds.net/~locowise/23-30.gif
Homework Equations
E=kq/r^2...
i just need to get this question over with
i tried and tried but i couldn't get the right answer plss anyone u.u
1. Homework Statement
point charges q1 = -6q and q2 = +3q are separated by distance d. Locate the point (measured from the origin at q1) at which the electric field due to...
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Sorry its sort of in...
Electric Fields is being taught in my A-level physics course but I don't really get it.
Firstly, we are given the equation Force= (Q1*Q2)/4*pie*permittivity*r^2 . But I don't know how it is derived. What area of Electric Fields should I research into to begin with?
Homework Statement
Two equal charges (Q = +0.80 nC) are situated at the diagonal corners A and B of a square of side x = 1.2 m as shown in the diagram. What is the magnitude of the electric field at point D?
Homework Equations
E=kQ/r^2
The Attempt at a Solution
First I converted...
hey guys i was wondering if anyone could help me with this question, kinda got stuck
Homework Statement
Figure 24-31 shows a section of a long, thin-walled metal tube of radius R = 5.56 cm, with a charge per unit length λ = 7.34 x 10-8 C/m. What is the magnitude E of the electric field at...
Homework Statement
http://session.masteringphysics.com/problemAsset/1001949/13/knight_Figure_25_69.jpg
An electric field 1.00×10^5 N/C causes the ball in the figure to hang at an angle. What is theta?
Homework Equations
E = F/q
F = mg
The Attempt at a Solution
The ball isn't...
Homework Statement
A small object A, electrically charged, creates an electric field. At a point P located 0.250m directly north of A, the field has a value of 40.0N/C directed to the south.
A) 1.11×10^−9C
B) −1.11×10^−9C
C) 2.78×10^−10C
D) −2.78×10^−10C
E) 5.75×10^12C
F)...
Homework Statement
Use Coulomb's law to determine the magnitude and direction of the electric field at points A and B in Fig. 16-57 due to the two positive charges (Q = 8.0 µC) shown. Is your result consistent with Fig. 16-31b?
Figure 16-57
Figure 16-31b
A)Find the magnitude of...
Homework Statement
1. Four charged particles are held fixed at the corners of a square of side s. All the charges have the same magnitude Q, but two are positive and two are negative. In Arrangement 1, shown below, charges of the same sign are at opposite corners. Express your answers to...
Hey, just wanted to check my method.
1)What is the distance between 2 protons experiencing a mutually repelling force of magnitude 4*10-11?
so for this, we have to use the formula for coulombs law--F=kq1q2/r^2
we know F and k. And q1=q2= 1.602*10-19. hence we can find r.
2)Two point...
suppose there is a region S through which the magnetic field changes with time then is the electric field induced there only or everywhere in space .
if everywhere what equations does it satisfy
Homework Statement
Charge of a uniform density (8.0 nC/m2) is distributed over the entire xy plane. A charge of uniform density (5.0 nC/m2) is distributed over the parallel plane defined by z = 2.0 m. Determine the magnitude of the electric field for any point with z = 1.0 m.
Homework...
Homework Statement
A hollow metal sphere has 6 cm and 10 cm inner and outer radii, respectively. The surface charge density on the inside surface is -100 nC/m^2. The surface charge density on the exterior surface is + 100 nC/m^2 .
What is the strength of the electric field at point 4 cm from...
E&M Electric Fields (Harmonic Motion?)
This problem comes out of "Physics (for scientists and engineers w/ modern physics) Volume 2 7th Edition" by Serway/Jewett
Review Problem Two identical particles, each having charge +q, are fixed in space and separated by a distance d. A third particle...
Homework Statement
1. The Earth has a net electric charge that causes an electric field at its surface equal to 150N/C and directed inward to the center of the Earth.
(a) What magnitude (and sign) of charge would a 60kg person have to acquire to overcome the weight of the force exerted by the...
Homework Statement
Hi, my question isn't actually over a particular homework problem, I've attached a file of my notes on electric field, electric dipoles, i don't quite understand why the equation of the electric field is setup that way for the negative charge.
Homework Equations...
Here is a question, which may seem dumb:
Consider an electron and a positron that annihilate, both of which are non-relativistic (taking the observer's frame of reference to be the center of mass frame of the electron-positron pair) so that we only consider their electric fields for simplicity...
Homework Statement
Two charges each +4 microcoloumbs ar eon the x axis, one at the origin and one at x=8m. Find the electic field at the x-axis at x=10m and x=2m.
Homework Equations
E=kq/r
The Attempt at a Solution
I tried the x=10m first. What I did was take E1=kq/r^2, or...
Why black holes can have static electric fields?
The gravitation of black hole is so strong that nothing can escape from it !
Why black holes can have static electric fields around with it?
Thank you in advance！
1. The magnitude of the electric field between two plates of a parallel plate capicitor is 4.7 x 10^4 N/C, if the charge on each plate increases by a a factor of 3, what happens to the electric field?
increase by a factor of 3 or 9?
decrease by a factor of 3 or 9?
not effected?
2...
Homework Statement
Two dipoles are oriented as shown in the diagram below. Each dipole consists of two charges +q and -q, held apart by a rod of length s, and the center of each dipole is a distance d from location A. If q = 3 nC, s = 1 mm, and d = 7 cm, what is the electric field at...
Homework Statement
What is the electric field at r1, r2, r3 for a solid sphere within a thick spherical shell where r1=1.5cm, r2=5.0cm, r3=8.0cm? The solid sphere has a total charge of 3C and the thick shell has a charge of -9C. a=2.0cm, b=4.0cm, c=6.0cm.
(a=radius of solid sphere, b=inner...
If a problem asks you to find the electric field at a certain point, do you add up the field vectors as if they were forces on a positive test charge?
For example:
I am having trouble figuring how the info given relates to electric and magnetic fields.
Homework Statement
A laser emits 1.38x10^18 photons per second in a beam of light that has a diameter of 1.96 mm and a wavelength of 518.0 nm. Determine each of the following for the electromagnetic wave...
Homework Statement
3. Two electrons are fired at 3.5 x 10^6 m/s directly at each other.
a)Calculate the smallest possible between the two electrons.
Homework Equations
Ek= 1/2mv^2
Ee= kq1q2/r
The Attempt at a Solution
I made the Ek and the Ee equal, but i keep on getting the...
Homework Statement
A negative charge of 2.4 X 10^-6 C experiences an electric force of magnitude 3.2 N, acting to the left.
a. Calculate the magnitude and direction of the electric field at that point.
b. Calculate the value of the field at that point if a charge of 4.8 X 10^-6 C replaces...
it is known that in metals the electric field is zero because there are free charges inside that rearranges in such a way that it cancels the external electric field.
If the external electric field is large enough, so large that all the free charge inside cannot rearrange itself to cancel the...
I am having some problem with the formulas for calculating the electric fields of an infinite line of charge and an electric dipole. I don't understand conceptually why they are the way they are. Can someone explain? Any help is appreciated!
[Note: K=1/(4*pi*epsilon_o), lambda=linear...
Homework Statement
Suppose a uniform electric field of magnitude 115.0 N/C exists in a region of space. How far apart are a pair of equipotential surfaces whose potentials differ by 2.0 V?
Homework Equations
1 N/C = 1 V/m
The Attempt at a Solution
I know 115.0 N/C is the same...
Homework Statement
A point charge q = +2.6 µC is placed at each corner of an equilateral triangle with sides 0.13 m in length.
What is the magnitude of the electric field at the midpoint of any of the three sides of the triangle?
Homework Equations
E=(kq)/r^2
Fx=(F1+F2)cos...
Homework Statement
A very long, straight wire has charge per unit length 1.47×10^10
At what distance from the wire is the electric field magnitude equal to 2.57 N/C
Homework Equations
E = lambda / (2*pi*E_o*r)
E_o = 8.85*10^-9
The Attempt at a Solution
2*pi*E_o*E / lambda...
Hi,
Homework Statement
You've hung two very large sheets of plastic facing each other with distance d between them, as shown in Figure P26.50 ( http://i137.photobucket.com/albums/q208/infinitbelt/p26-50-1.gif ... ). By rubbing them with wool and silk, you've managed to give one sheet a...
Trying to work this one out.
If you have two charges Q1 and Q2 separated by a distance of x then how do you show what distance from the charge Q1 is the total electric from the two charges zero.
I know that Enet =E1 +E2 and if i use coulombs law i get:
KQ1/x^2 +KQ2/x^2
the K cancles...
I haven't taken any course in quantum field theory or read any advanced books about it, but I would like to make what I think is a deduction.
An electric field can be explained by changing magnetic field. Provided that some property of this changing magnetic field was met, the electric field...
In Millikan's experiment, an oil drop of radius 0.9493 µm and density 0.876 g/cm3 is suspended in chamber C (Figure 22-14) when a downward-pointing electric field of 1.92 105 N/C is applied. Find the charge on the drop, in terms of e. (Include the sign.)
So, to do this problem, i know that...
magnetism and electric fields
Hello all. I'm new to this, but I would really appreciate any help, I'm absolutely terrible at physics...
1) In a trial of Millikan's oil drop experiment, we find that the electric field required to suspend a tiny oil particle with mass 1.46x10^-14 kg is...
Purcell said "One must be alert for every opportunity to bring the students into the world where an electric field is not a symbol merely, but something that crackles."
Why does an electric field crackle? Is it because electric fields are lines which connect charges, enabling them to exert...
Here's the question:
A square plate of copper with 50.6 cm sides has no net charge and is placed in a region of uniform electric field of 80.9 kN/C directed perpendicularly to the plate.
a. Calculate the charge density of each face of the plate.
b. Calculate the total charge on each...
Here is the question:
Three identical small Styrofoam balls (m = 1.93 g) are suspended from a fixed point by three nonconducting threads, each with a length of 49.0 cm and with negligible mass. At equilibrium the three balls form an equilateral triangle with sides of 29.2 cm. What is the common...
I have a question about electric fields:
Here is the question:
Three identical small Styrofoam balls (m = 1.93 g) are suspended from a fixed point by three nonconducting threads, each with a length of 49.0 cm and with negligible mass. At equilibrium the three balls form an equilateral...
Consider a long horizontal conducting wire with charge density
= 5.70*10^-12 C/m. A proton (mass = 1.67*10^-27 kg) is placed and
released 0.820 m above the wire. What is the magnitude of initial
acceleration of the proton?
My thought is: a=q*E/m
and E is: 2*k*charge density/distance...
An iodine (-1) and a chloride ion (-1) interact in a vaccum.
a. What is the force which each exerts on the other from a distance of 2.0 x 10^-9 m?
b. What is the eletric field that the iodine ion experiences from the chloride ion? toward which ion does the electrical field vector point...
Hi, I am currently stuck on the following questions. Any help is greatly appreciated. thank you
*all question are algebra based
1) A point charge of -0.90 microC is fixed to one corner of a square. An identical charge is fixed to the diagonally opposite corner. A point charge q is fixed to...
Hi, sorry if this is a frequently asked question.
I was reading up on black holes with electric charge and I was wondering how the electric field is able to propogate out of the singularity and the event horizon, if anything moving at the speed of light cannot escape.
The only explanation...
Hello, everyone. I have a problem that I solved using Gauss's Law. However, I am unconfident in my answers, as I have very little experience with Gauss's Law.
The surfaces of two large (i.e. infinite) parallel conducting plates have charge densities as follows: \sigma_1 on the top of the top...