For questions that utilize the concept of electric fields (commonly denoted by the letter E), or for questions whose answers likely involve electric fields. More specific than the [tag:electricity], as questions about the phenomenon & theory of electricity do not necessarily involve the discussion ...

learn more… | top users | synonyms (1)

0
votes
1answer
243 views

Mean-free-time between collisions and drift-velocity

In a physics text book I need help to make sense of the part highlighted in yellow: This is out of context of course, so just to make it clearer: $\tau$ is the mean free time of the electrons in a ...
1
vote
1answer
121 views

Upper limit to electric charge confinement?

The following questions are not intended for conventional capacitors (which stores excess charge on the outside surface), rather a type of hypothetical capacitor which is designed to confine charge by ...
2
votes
1answer
170 views

Does a static electric field act continuously?

Electromagnetic radiation is emitted and absorbed in discrete units, photons. One photon's energy is described by the well known $E = hf$ formula. Now, if you a have static electric field that ...
4
votes
1answer
233 views

Simulate / plot electrostatic field

I have something like this: For given voltage (9 V red wire, 0 V blue wire) I want to simulate electrostatic field. I already know, for example that in the point (10.5;0) there are 10 V and etc. I ...
0
votes
1answer
97 views

Electric Potential Energy

When work is done on a positive test charge by an external force to move it from one location to another, does the potential energy increases or decreases, and does the electric potential increases or ...
2
votes
6answers
7k views

Why do we test electric fields with positive charges and not negative ones?

Is there any difference between using a positive versus a negative charge to test an electric field?
0
votes
2answers
45 views

When is work done on or by something?

An example, here what my textbook says: When charges are released In electric fields charges experience the force causing them to accelerate along electric field vectors. Positive charges ...
0
votes
0answers
12 views

To change the path of an electron beam travelling horizontally using a uniform electric field [on hold]

Problem: A beam of 20kV electrons is travelling horizontally. If one was to bend the path to make them travel vertically at the same speed, using a region with a uniform electric field, what are the ...
3
votes
2answers
592 views

Why electric field inside charged conductor is zero in the electrostatic case?

I am trying to understand the idea (or the fact) that most books introduce which is about the electric field inside a charged solid conductor Books tell that the field has to be zero everywhere ...
1
vote
1answer
40 views

Electric field between capacitors [on hold]

A parallel-plate capacitor consists of two parallel, conducting plates of area $A$, separated by a distance $d$. Each carries a charge of magnitude $Q$; positive on one, negative on the other. ...
0
votes
0answers
14 views

Why the magnitude, $E$, of the field vector is different for every sets of (parallel) plates?

This is quoted my textbook. I wonder why we can't reproduce the same magnitude on a different set of plates, if we make them the same size, same charge, and having the same electric potential, and ...
0
votes
3answers
64 views

Which one of the two objects does the gravitation force vector point to?

My book tells me that the arrowhead should point to whichever is responsible for the field. Am correct in a assuming that it's whichever has the larger mass or bigger electric charge?
2
votes
1answer
143 views

Static electricty and fields inside of the conductor?

I have a few related questions about static electricity and conductors. 1. when we say static electric field inside a conductor is zero, let us take an example of two concentric conductors, outer one ...
2
votes
1answer
40 views

What do field lines between two like-charged parallel plates look like?

I couldn't find any image to answer my question on Google. But I guess it looks somewhat like this, correct?
0
votes
1answer
18 views

Why can't objects made of insulating material “store excess charges”?

This is quoted from my textbook. I saw plastic objects before being able to store excess charges. For example, if you rub paper against a plastic pole. Both will gain charges. But in lab, I never ...
1
vote
1answer
51 views

Why isn't the electric field zero in the empty space?

A spherical portion has been removed from solid sphere having a charge distributed uniformly in its volume the electric field inside the emptied space is? Isn't the electric field suppose to be zero ...
1
vote
1answer
104 views

Microscopic fields inside a conductor

In a neutral conductor if we assume electrons as point charges, the electric field in the space between them cannot be identically zero. This microscopic field may be very weak. What if we were very ...
2
votes
1answer
91 views

Electric Field inside a diode

When a voltage is applied to a diode (Forward or Reversed bias) the depletion zone is changed due to charges change in this region. My question is in both case (Forward or Reversed bias), how the ...
1
vote
0answers
17 views

Imaging and the Electric Field

In this book (pg. 162), it mentioned that conventional lenses only focus propagating waves, thereby creating an imperfect image. In contrast, superlenses focus both propagating and evanescent waves, ...
1
vote
2answers
213 views

How do electrons distribute themselves along a wire attached to one pole of a battery?

Let's assume we have an electrochemical cell, like an AA battery. We attach a long straight wire to the negative terminus of the battery, the other end of the wire extends right away from the battery ...
1
vote
4answers
241 views

What is the *cause* of the Lorentz Force

Is it possible to explain what actually causes the force on a current carrying conductor in a magnetic field. I have read that this is due to the magnetic fields 'interacting' in some way. This ...
0
votes
1answer
27 views

How do I get the angle for the $x$ and $y$ component of the electric field for four equidistant particles?

Four particles form a square of edge length $a= 5.00\ cm$ and have charges $q_1= +10\ nC$, $q_2=-20\ nC$, $q_3=20\ nC$, and $q_4=-10\ nC$. In unit vector notation, what is the net electric field the ...
2
votes
1answer
125 views

Why does the potential difference between two charged plates increase as they move further apart?

Suppose a uniform electric field $E$ exists between to oppositely charged metal plates (one is positively charged and one is negatively charged). If the plates move apart, and the charges on each ...
1
vote
1answer
380 views

Apply Gauss' law to find electric field around nonconducting plastic sheets

The question: Two very large, nonconducting plastic sheets, each 10.0 cm thick, carry uniform charge densities $\sigma_1$,$\sigma_2$,$\sigma_3$ and $\sigma_4$ on their surfaces, as shown in the ...
1
vote
1answer
40 views

How to calculate the potential energy of an $H_2$ molecule

From left to right, electron $e_1$, $e_2$ and proton $p_1$, $p_2$. $r_0=0.529nm$ The total energy is sum of energy require to bring each particle to its place. Take the place of $e_1$ is zero ...
0
votes
0answers
44 views

Does voltage depends on the charge present in an element?

Does the voltage depend on the charge present in a battery ? I know in capacitors q=cv. Hence charge present is proportional to voltage. Is it the same in the case of batteries?
-1
votes
5answers
144 views

The potentiality of the electric field

Could you please explain using just words why electric the field is potentially? I know the proof using integral: $$A = \int_{12}q\vec{E}\cdot{d}\vec{r} = qQ\int_{12}\frac{\vec{r}\cdot{d}\vec{r}}{r^3} ...
1
vote
3answers
57 views

Is the electric field at a single point inside a charged sphere zero?

Many physics textbooks say, Gauss' law shows that the electric field inside a sphere with uniform charge distribution on the surface equals zero. What I want to know is, do they mean total, ...
1
vote
1answer
194 views

What factors cause the velocity saturation to occur at different electric fields for different materials?

In semiconductors the velocity of carriers gets saturated after a certain value of electric field. In silicon it occurs at around $10^4 kV/cm$ and in GaAs at some other value. What factors are ...
0
votes
1answer
100 views

How can electric field representation be obtained from Enge representation using Maxwell's equations?

Suppose we have a long electric capacitor. Let $L$ be its length ($z$ coordinate), $W$ its width ($y$ coordinate), and $D$ its full height (full aperture; $x$ coordinate). Let $L\gg W\gg D$. The ...
0
votes
0answers
23 views

Finding Magnitude and Direction of Dipole's Electric Field at a Point

This question pertains to finding the magnitude and direction of a dipole's electric field. Specifically, I am trying to figure out why we are using both the hypotenuse and $\sin\theta$, and not the ...
0
votes
1answer
85 views

Does the electric field inside a circuit cause a potential drop with distance?

We know that when the system reaches steady-state(current does not change with time),the electric filed inside the circuit is constant. In many textbooks and lectures,professors make a graph like this ...
6
votes
3answers
25k views

In electrostatics, why the electric field inside a conductor is zero?

In electromagnetism books, such as Griffiths or the like, when they talk about the properties of conductors in case of electrostatics they say that the electric field inside a conductor is zero. I ...
1
vote
3answers
401 views

Does a conductor need to touch the battery terminal for electric field to be set up inside it?

I understand that an electric field is setup inside a conductor when it is connected to the terminals of a battery and that this field is caused by induced surface charges on the conductor. These ...
0
votes
1answer
186 views

Dielectric sphere placed in another dielectric medium with uniform external field: is there a surface charge density?

Consider a dielectric sphere placed within a dielctric medium. There is a uniform electric field $E_0$ present throughout in the medium. Would there be surface charge on the sphere?
0
votes
0answers
28 views

Where can I find a good theoretical treatment of conductor shielding?

Suppose one has three current carrying cylinders lying on the same plane. Some of the electric field of the first conductor ends up on the second conductor, which creates capacitance C12. But also ...
0
votes
1answer
79 views

Electric field due to an electric dipole at a point on the equatorial line

According to [tamilnadu][1] textbook Electric field due to an electric dipole at a point on the equatorial line is given as The direction of E is along ...
2
votes
3answers
127 views

Vector decomposition validity

Is force or field decomposition into component vectors always valid? Lets say a constant electric field $\vec{F}$ is acting in space such that it makes an angle $\phi$ with respect to the horizontal ...
4
votes
2answers
5k views

Why is the electric field perpendicular to every point on the surface of a conductor?

I am reading Berkeley Physics Course, Volume 2 (Electricity and Magnetism by Edward M. Purcell). I am in chapter $3$, page $92$, and the book discusses conductors. The following is from the book: ...
0
votes
1answer
45 views

Fringing effect of electric current

We know the what is the fringing effect of electric field in capacitor, of magnetic field in some in some solenoid or magnetic field in through joint of some metal. But is there is something similar ...
0
votes
0answers
57 views

$E$-field from changing current in straight wire

A very long insulated wire oriented along the $z$ axis of a cylindrical coordinate system is carrying current that is defined by the following function: $$I(t) =Io + k⋅t$$ (current increases linearly ...
0
votes
2answers
5k views

Conversion of Moving coil galvanometer to ammeter

A galvanometer can be converted into an ammeter by connecting a low resistance (called shunt resistance) in parallel to the galvanometer. Firstly, why do we need to connect the resistance? If a ...
2
votes
3answers
459 views

Why the electric field $\vec{E}$ is constant (=position independent) for an infinite 2D sheet of constant charge?

So I'm reading a text on electricity and it talks about using the integral to compute the total charge of a collection of points, which I mostly understand. But then we get to finding the electric ...
2
votes
1answer
58 views

Can electric field lines “sometimes” pass through conductors' surfaces?

I have a rather general question about electric field lines. If we have a hollow and neutral spherical shell and we place somewhere inside it a charge QA=+q, the electric field outside of the ...
1
vote
2answers
155 views

Ion Optics: Electric and Magnetic field. A comparison with Light Optics

When we compare ion optics with light optics, normally we consider electric field. For example Snell's law. $n_1\sin\theta_1$=$n_2\sin\theta_2$. When an electron move from one electric potential to ...
0
votes
1answer
48 views

Why is this electric field due to one plate of a capacitor $\sigma / 2 \epsilon_0$ when the capacitor plates are finite?

We know that electric field due to an INFINTE large sheet is constant and at INFINTY the electric field is not zero. But say if I take a finite sheet of length l and width w. Then the electric field ...
0
votes
0answers
17 views

How does one start drawing electric fields? [duplicate]

How does one start drawing electric fields.you are given two charge.now there are infinite electric field lines so how do you show greater electric field by drawing denser lines.After all there can be ...
3
votes
2answers
67 views

Why is the electric field highest in regions of highest resistance?

I know Kirchhoff's law and that current must be constant. But what exactly is the phenomenon, from first principles, that causes the electric field to be stronger in a region with lower carrier ...
1
vote
2answers
75 views

Why is the Electric Field Zero at this point?

In a Phet Lab simulation, which is all I have at the moment to do my learning on electric field forces, the point represented as colored on the diagram below is shown to have an electric field ...
0
votes
0answers
24 views

Sign of an electric field in electric potential energy problem

I was wondering why the electric field E in this problem is negative. Is it because the earth is negative? We can assume that near the Earth’s surface, a uniform electric field is set up thanks to ...