What is Electric field: Definition and 1000 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 three parallel planes of charge shown in the figure have surface charge densities (-1/2)η, η, and (-1/2)η.
Homework Equations
I think that the electric field is equal to eta divided by epsilon naught.
The Attempt at a Solution
Well, I know that the electric field at...
Homework Statement
Homework Equations
Gauss
The Attempt at a Solution
I am really confused with question a, I have an idea of how to answer b and c once I obtain an answer for part a... My best guess would be to use Gauss, but I am not sure. Would the field inside be 0? What will the bounds...
Homework Statement
Find the electric field at a distance z above the center of a flat circular disk of radius R
Homework EquationsThe Attempt at a Solution
My attempt to solve this was take the line integral from the center of the circle to the edge. Then, knowing the circle is symmetrical...
Homework Statement
The membrane around a cell normally has layers of charge that create a potential difference between its outer and inner surfaces. This difference is about 72 mV .
When a singly ionized potassium ion moves through a channel in the membrane passing from the outside to the...
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...
Homework Statement
The electric potential at points in an xy plane is given by V = (1.5 V/m2)x2 -(2.9 V/m2)y2. What are (a) the magnitude of the electric field at the point (3.9 m, 2.9 m) and (b) the angle that the field there makes with the positive x direction.
Homework EquationsThe Attempt...
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...
Homework Statement
[/B]
Derive expressions for the magnitude and direction of the electric field at point P and the potential
at R.
Charges Q1 and Q2 are both positive.
Distance from Q1 to P is h, distance from Q2 to P is √2 h
Homework Equations
E = k q/r^2
The Attempt at a Solution
I...
Homework Statement
(a) What is the strength of the electric field at the position indicated by the dot?
(b) What is the direction of the electric field at the position indicated by the dot? Specify direction as an angle measured ccw from the positive x-axis.
##Q_{1} = 4.0 C##
##Q_{2} = 9.0...
Homework Statement
##e_{r1}=2##
##e_{r2}=10##
##α_1=\pi /4##
##D_1=100 nC/m^2##
##ρ_s=0##
On the borderline of two dielectrics there is no free charge. Calculate the surface bond charge density of both dielectrics.
##ρ_{bs1}=?##
##ρ_{bd2}=?##
Homework Equations
3. The Attempt at a Solution...
What composes the E Field of the Electromagnetic Wave where "disturbances" for propagation occurs?
If electromagnetic waves cause disturbances in the Electric Field… what “is” in this E Field which photons Interact with?
I ask because in Vacuum, there are no electrons to excite. So what is...
Homework Statement
Homework EquationsThe Attempt at a Solution
Okay, parts a-c are zero as they are within both shells.
Lets begin with d because i fear I am just repeating the same error in all of the following parts.
Part d
qenclosed=ρ(4πr^3/3-4πa^3/3)
=...
What I Think I Understand: ΔV = Ed (d being dstance) and that V = kq/r
please correct me if I'm misunderstanding those.
What I need to know: When E = 0, what happens to the electric potential? and vice versa.
Me Working it out: So if i use the first equation up here, If E = 0, then electric...
Homework Statement
Two pairs of charges are shown in Figure 1.
Homework EquationsThe Attempt at a Solution
I originally thought that the electric field past point 7 (i.e. points 8,9, 10) was the solution. However, this is wrong. I then considered point 1, yet that was wrong too. I even...
Homework Statement
A washer made of nonconducting material lies in the x − y plane, with the center at the coordinate origin. The washer has an inner radius a and an outer radius b (so it looks like a disk of radius b with a concentric circular cut-out of radius a). The surface of the washer is...
Homework Statement
A thick, spherical shell of inner radius a and outer radius b carries a uniform volume charge density ρ.
Find an expression for the electric field strength in the region a<r<b.
Homework Equations
Gauss's Law ∫E⋅dA
Area of a sphere
The Attempt at a Solution
I know I am...
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...
Homework Statement
A 10-nC point charge is located at the center of a thin spherical shell of radius 8.0 cm carrying -20 nC distributed uniformly over its surface.
What is the magnitude of the electric field 2.0 cm from the point charge?
Homework Equations
E = kq1q2/r^2
The Attempt at a...
Homework Statement
Homework Equations
σ=q/(4πr^2)→q=σ(4πr^2)
E=q/(4πEod^2)
E=(4πr^2σ)/(4πEod^2)The Attempt at a Solution
So the first thing that i could include was that the point p was inside Shell 1 and therefor would not be affected by Shell 1.
So it should be a fairly simple plug in the...
Homework Statement
The problem statement is in the attachment
Homework Equations
E[/B] = -∇φ
∇ = (∂φ/∂r)er
The Attempt at a Solution
I am confused about how to do the derivative apparently because the way I do it gives
E = - (∂[p*r/4πε0r3]/∂r)er = 3*(p*r)/4πε0r4er
Homework Statement
Homework Equations
Enetx=((kq1)/r^2 +^2) with the pos/neg of the coefficients being dependent on the position of the charges around the point
The Attempt at a Solution
As everything is one dimensional we can assume the j an k compnents of the electric field are 0
Part a...
Homework Statement
Figure (a) shows charged particles 1 and 2 that are fixed in place on an x axis. Particle 1 has a charge with a magnitude of |q1| = 19e. Particle 3 of charge q3 = +16e is initially on the x axis near particle 2.Then particle 3 is gradually moved in the positive direction of...
http://imgur.com/a/Hg23p 1. Homework Statement
In each of the figures below some electric field lines are drawn. But in most cases, there are mistakes. For each drawing, select which of the above rules are broken or if the diagram is essentially correct.
http://imgur.com/a/Hg23p
Homework...
Homework Statement
Written Problem: Summing the Electric Field Three point charges q1, q2, and q3 are placed along a straight vertical line to create a “tripole”. At point P, which is directly to the right of q1, the net electric field is exactly zero. We also know that q1 = 1 μC.
b) Write a...
Homework Statement
Homework Equations
L=pi*r/2
λ=q/L
Enet=∑λ(2sinθ)*kThe Attempt at a Solution
So first to calculate L for each arc
L1=pi(.107m)/2
L2=pi(.214m)/2
L3=pi(.321m)/2
and lambda:
λ1=3.3E-6/L1=2E-5
λ2=-12E-6/L2=-3.9E-5
λ3=29.7E-6/L3=5.9E-5
So using θ=pi/2 and rearranging the...
Hello,
In classical electromagnetism, we learn that an electric charge generates and electric field which other charges can feel through a force. But the source charge does not feel its own generated electric field.
In reality, a charge feels its own field. Why are we able to ignore this...
Homework Statement
Homework Equations
Ex=1/k*1/(a^2/2)*1/(sqrt2)*cos(theta)*(sum of charges)
Ey=1/k*1/(a^2/2)*1/(sqrt2)*sin(theta)*(sum of charges)
The Attempt at a Solution
So first off I can see that I don't need to calculate the force in the x direction as each q cancels out when...
Homework Statement
A proton is at the origin and an electron is at the point x = 0.36 nm , y = 0.34 nm.
Find the x- and y-components of the electric force on the proton.
Homework Equations
E = kQ/r2
The Attempt at a Solution
So I found that E = 9.38 * 10-28, but my problem is that I do not...
Homework Statement
A 60 μC point charge is at the origin.
Find the electric field at the point x1 = 50 cm , y1 = 0.
Homework Equations
Coulombs Law: F = (kQ1Q2)/r2
Electric Field: E = kQ/r2
k = 8.99*109 C
The Attempt at a Solution
So taking Coulombs Law and deriving the Electric Field...
Homework Statement
Homework EquationsThe Attempt at a Solution
I figured you could consider it as infinitely many rings? Here is what I did so far:
I feel like 0 is the wrong answer. Can anyone help me? Thanks.
Homework Statement
There's a charged semicircle, the ends of which are on the x-axis and it extends into the positive y-axis. It has uniform line charge density. I need to find the electric field at an arbitrary point on the x-axis that's not the origin.
Homework Equations
I don't know.
The...
Homework Statement
What is the electric field at the center of a hemisphere bounded by r=a, 0<θ<pi/2 / and 0<∅< 2pi with a uniform surface charge density?
Homework Equations
(1/4piε0) ∫ p(r') ((r-r')/[r-r']^3) dr'
The Attempt at a Solution
Forgive my formatting
ds= (r^2)sinθdθd∅ (In direction...
Homework Statement
Homework Equations
'
The Attempt at a Solution
Please excuse the poor writing. I believe it should be legible enough, but if you have any questions, i'll clarify or rewrite it.
Please excuse the poor writing. I believe it should be legible enough, but if you have any...
Homework Statement
Two parallel plates 1.40 cm apart are equally and oppositely charged. An electron is released from rest at the surface of the negative plate and simultaneously a proton is released from rest at the surface of the positive plate. How far from the negative plate is the point at...
Field at End of Line of Charge 2
A charged rod of length L=7.10 m lies centered on the x axis as shown. The rod has a charge density which varies according to λ=ax^2 where a=−20.2 μC/m^3 .
What is the x component of the electric field at a point on the x-axis a distance of D=3.70 m from the...
1. Homework Statement
Hi everyone, I am having trouble solving this question. I know that the right answer is d.
Homework Equations
No equations here, only conceptual stuff.
The Attempt at a Solution
Say I have the following points: A and B
A...
Homework Statement
A thin semicircular rod is broken into two halves. The top half has a total charge +Q uniformly distributed along it, and the bottom half has a total charge -Q uniformly distributed along it. A negative test charge is placed at points A, B, and C.
*Image attached*
Consider...
Homework Statement
A thin semicircular rod has a total charge +Q uniformly distributed along it. A negative point charge -Q is placed as shown. (Point C is equidistant from -Q and from all points on the rod.)
*Image Attached*
Let Ep and Er represent the electric fields at point C due to the...
Hi everyone, I am having problems figuring out how to solve a particular problem.
Because I was not able to access PhysicsForums recently, I typed everything about my issues into a pdf file that I have attached below.
I am grateful for your help in advance, and make it a great day...
Hello
A friend of mine asked me if he could improve the (amateur) characterization of minerals by studying the absorption spectra during the application of a magnetic field.
I thought that maybe the electron cyclotron resonance could work, but then I noticed that very low temperatures are...
1. Homework Statement
i was solving the 2008 semi final us physics olympiad paper when i got stuck on question B2 in part 2
http://www.aapt.org/Programs/contests/upload/olympiad_2008_semi-final_soln.pdf
the link takes you a pdf with questions and solution however i don't understand the soution...
When a charge placed at anywhere,then it produces a powerful field around itself,is called electric field. It is exist whenever charge exist.And charge takes very very small time in propagate electric field.
It is a simple arrangement. Imagine that we have an empty cubic box. Outside the box the electric potential is infinite. Imagine that you put an electric charge at the geomectric center of the box. What is the field around this charge? In other words, the tool I have to calculate the field...
Homework Statement
https://imgur.com/zEoCpc0
I am trying to figure put the angle and my attempt is tanx=sy/sx (I have calculated a value for the distances)
But my book is saying: tanx =vy/vx
I don't understand why my way of solving it is wrong... I don't get the same answer for x :/
Homework Statement
a) Find the net force on charge 1.
b) What is the net electric field acting on charge 1?
Please see the attached files to view the image that goes with the questions above.
Homework Equations
I'm having trouble with this unit in general and I'm not to confident in these...
I understand that as a solid melts, it increases can increase in polarizability of the medium, and increase the Dielectric constant (K).
-ex. like dissolving NaCl and having ions in solution.
Why does Thermal motion reduce the polarizability of the medium, thus decreasing the dielectric...
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...
Hi,
If I had a charged parallel plate capacitor which was not connected to a circuit (so the charges stay on the plates) creating an electric field strong enough to cause ionization, and I then fired a neutral atom between the charged plates (the charge starts outside of the electric field)...