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0answers
35 views

Electric field at a point [on hold]

We consider a thin disk whose center is $O$ and radius is $R$, which has an electric surface charge density of $\sigma$. We want to find the expression of the electric field $\vec{E}$ at a point ...
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1answer
33 views

Electric field and potential between two charges [on hold]

There are two point charges on the $x$ axis and $x'$ is a place where the potential, relative to infinity, is the biggest. Why is the electric field zero at this point?
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0answers
29 views

Calculate electric field without using Gauss law

Given a uniformly charged sphere ( total charge $5 nC$ ) of radius $R=10 cm$, write the equation of electric field vector for any distance $r (r > R)$ from sphere center and calculate total ...
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0answers
21 views

Capacitance between multiple conductors [closed]

So, I am having trouble figuring out the capacitance of systems like these( 3 parallel wires) First and third are connected so their potentials are the same, and since their radii are also the same ...
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1answer
19 views

Finding voltage between two points in space

If electric field vector is defines as : $\vec{E} = \frac{V_0x^2}{a^3} \vec{i_x} + \frac{V_0y}{a^2} \vec{i_y} $ where $V_0 $ and $a$ are known constants, $\vec{i_x}$ and $\vec{i_y}$ unit vectors of ...
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1answer
15 views

Electrical charge equilibrium and the piezoelectric effect

About the piezoelectric effect: if I press a crystal the electrical charges segregate and an electrical voltage appears on the other two faces of the crystal. See this link for example: ...
0
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0answers
14 views

Electric field due to continuous volume charge distribution [duplicate]

Since the Electric field at point (0,0,z) is $$dE = \frac{\rho vdv}{4\pi\epsilon_0R^2}\hat{R}$$ $$\hat{R} = \cos\alpha \hat{z} + \sin\alpha \hat{\rho}$$ where $\hat{R}$ means unit vector $R$. ...
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0answers
17 views

Electric Field Resulting from a Conductor

In preparation for an upcoming exam, I've been attempting to visualize the electric field produced by a conductor in a variety of situations. I asked myself the following question and attempted to ...
0
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2answers
32 views

Calculate expected Voltage at a distant electrode

Firstly, please forgive me for misconceptions and errors as my knowledge of Physics is very basic. I have EEG data (uV vs time) traces for an array of platinum electrodes placed on the surface of ...
0
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1answer
22 views

2 spheres both negative or positive [closed]

Two small charged metal spheres A and B are situated in a vacuum. The distance between the centres of the spheres is 12.0 cm, as shown in Fig. 4.1. The charge on each sphere may be assumed to be a ...
1
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0answers
28 views

What is the electric field near an infinite sheet with a point charge near by? [closed]

The electric field near a negatively charged conducting infinite sheet is $\frac{-\sigma}{2\epsilon}$. If we add an equally charged positive particle some distance $r$ away from the sheet, the field ...
0
votes
1answer
33 views

Parallel plate capacitor

How does a parallel plate capacitor emit a constant electric field between its plates? Isn't the electric field governed by an inverse square law? Then what would happen if I put a charged particle ...
1
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1answer
65 views

Energy Stored In A Capacitor (Slowly Moving Parallel Plates Together)

I think this is a canonical problem with capacitors, but I'm having difficulty understanding the paradox. In Purcell's Electricity And Magnetism, problem 3.16 reads: Calculate the electrical ...
2
votes
3answers
86 views

How come we talk about gravitational potential energy and not gravitational potential?

With regards to gravity the equation learned is $$U=-\frac{GMm}{r}$$ And the relationship to force is $$F=-\frac{dU}{dr}$$ In electrostatics we instead talk about electric field and electric ...
2
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2answers
49 views

$ε_0$ affects electric field intensity, but $μ_0$ doesn't affect magnetic field intensity?

I'll be honest: this question is actually a homework problem. I've spent the past hour going through Google and several textbooks trying to answer the question "Why does $ϵ_0$ affect electric field ...
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2answers
52 views

What is the speed of an electric spark/arc in vacuum?

I am just curious about the nature of an electric spark, how fast are the electrons moving? Will these electrons slow down when the spark occurs through a dielectric? (e.g., air)
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0answers
57 views

Electrical field of the coil

Take the case of two coils, first one connected to alternating current supply, and the second one connected to load. First coil creates magnetic field, and electric field is reduced by anti-emf ...
0
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1answer
39 views

Image charge method to find electric field [closed]

The following is a question from my tutorial on boundary value problems and image charge method- A point charge +q is placed at (0, 0, d) above a grounded infinite conducting plane defined by z = 0. ...
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0answers
27 views

Why is voltage input different from voltage output in a circuit?

This is more specifically, when performing the meter bridge experiment. The meter bridge experiment is an experiment in which using the meter bridge, a jockey, voltmeter, battery eliminator, you keep ...
1
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1answer
88 views

Can the electric field strength of a wire simply be calculated using the voltage / length formula?

Can the electric field strength of a wire simply be calculated using the voltage / length formula: Electric Field Strength = Voltage Across Wire/ Length of Wire I am asking about a wire with current ...
0
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1answer
24 views

Finding electric field of a line charge [closed]

I have a bit of an issue setting up the integral for finding an electric field of a particular scenario. The scenario is that a line charge of length R is a distance R from the left side of the ...
0
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0answers
27 views

Could a 1kHz EM field be detectably disturbed by an action potential?

This might be completely off base, but I'm wondering if this would be possible. Neurons fire action potentials that can be modeled as low-intensity (~100mV) EM pulses of 1kHz frequency (up and back ...
0
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1answer
78 views

Why isn't the electric field just a mathematical tool?

I'm limiting my question to this field because it is the only one I know of with a certain degree of knowledge. I doubt they really exist because of the following reasoning: Coulombs law was stated ...
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0answers
21 views

Determining if an object is dielectric or metallic

In a worksheet I was given, I had to find the net electric field of P which is L distance away from a bar. The last question is ...
1
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0answers
14 views

Can we use EEG to record signal from spinal cord?

My hype is about the idea that Spinal cord around neck is the place every signal sent to control whole body. So if we can record all signal, we could analyze movement of our body from finger to leg ...
0
votes
1answer
175 views

Gauss Theorem:Electric field of an uniformly charged non-conducting spherical shell

I want to know the electric field of an uniformly charged non-conducting spherical shell. I know that in case of conductors(metals),the sphere can be shell or it can be solid,but in both the cases ...
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2answers
53 views

Draw the charge configuration according to the electric field [closed]

I'm trying to draw the charge configuration outside the regions that lead to the given electric field patterns. Can someone show me how?
31
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5answers
3k views

How is it possible to accelerate a neutron?

It is possible to accelerate a charged particle in an electric field, how is it possible to accelerate a neutron? How can we control its velocity?
0
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1answer
33 views

Why don't neutral atoms distort the electric field?

Suppose I have a positively charged conductor with a cavity. There's a positive charge inside the cavity and the system has reached electrostatic equilibrium. Then there's negative charge surrounding ...
3
votes
2answers
107 views

Physical meaning of imaginary part of Electric field?

As far as I know (or I thought I knew), if we have an electric field $$\mathbf{E}=\mathbf{E_0}\cos(\omega t - kx),$$ we can define it as the real part of $$\mathbf{E}=Re(\mathbf{E_0}e^{i(\omega t - ...
0
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2answers
52 views

What is the difference between electric charge and electric flux?

What is the difference between electric charge and electric flux? According to my knowledge electric flux is nothing but electric charge enclosed by the closed surface.
2
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1answer
44 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 ...
-1
votes
1answer
36 views

Electric Field of a sphere

Is there a point in space where the electric field is half of the electric field on the surface of the sphere? I just got curious if it would be possible.
0
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1answer
15 views

How is electric field strength related to potential difference?

I was looking at the derivation of drift velocity of free electrons in a conductor in terms of relaxation time of electrons. Here a metallic conductor XY of length $\ell$ is considered and having ...
2
votes
1answer
60 views

Definition of a field line?

Ok so I finished by A-levels last year (english exams 18 year olds take) and we defined in my physics course we defined field lines (for an electric field) as: The path a free positive test charge ...
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2answers
25 views

Direction of current in concentric cylinders

Example 7.2 in David Griffiths E & M book (3rd edition) has a side view of 2 concentric cylinders, with smaller radius $a$ and larger radius $b$. The region in between $a$ and $b$ has ...
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0answers
13 views

Measuring polarization of a neutral object near a charged sphere

I am trying to design an experiment where I can calculate the distance at which polarization will not have a measurable effect on a neutral object, from a sphere charged by a Van Der Graaf generator. ...
1
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1answer
41 views

How to find whether the electric field between capacitor plates is above or below the electrical breakdown limit of the insulator between the plates?

Let's say the two plates of a capacitor have charges $q_1$ and $q_2$. The separation between these plates is $d$. I know that I can calculate the electric field by dividing the voltage that is applied ...
0
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1answer
29 views

The difference between EMR and lone Electric and Magnetic fields

I fail to understand the true difference between EMR and electric and magnetic fields. When current flows, there is an electric field due to the electron flow and a magnetic field, however no EMR ...
0
votes
1answer
47 views

How does electric field intensity look like along a wire which has one end connected to an AC source and the other one is left free?

How does the electric field intensity look like along a wire with constant conductivity which has one end connected to an AC source and the other one is left free? I mean is the electric field the ...
0
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1answer
246 views

Electric field strength at the center of an equilateral triangle

Questions: Three $x$ m long rods form an equilateral triangle. Two of the rods are charged to $+q$ C and the third to $-q$ C. What is the electric field strength at the center of an equilateral ...
2
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1answer
52 views

Proving the equivalency of the potential energy of a system of charges and the work required to assemble a system of charges

This is a very cool, and highly beneficial problem in my opinion. I feel as though truly understanding this proof would broaden anyone's conceptual understanding of electric potential. My textbook ...
1
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0answers
66 views

Sign error in calculating the electric field of point charge

I have to determine the electric field of a point charge, I get a true result except for a sign. Here is my passages. $$\nabla \cdot e = \frac{\rho}{\epsilon}$$ $$e = - \nabla u$$ $$\nabla^2 u = - ...
1
vote
1answer
42 views

Uniformly charged sphere's electric field

I am facing this topic for the umpteenth time in my college career and, of course, every teacher has explained it in a different way. In this course, to find the expression of the electric field of a ...
1
vote
1answer
58 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 ...
3
votes
1answer
113 views

Why are atomic quadrupole moments calculated using nuclear spin?

It's my understanding that electric quadrupoles interact with the gradient of an electric field, and I understand roughly how this works. I am trying to calculate the interaction between an atomic ...
2
votes
1answer
35 views

Electric Field-Drift Velocity

Why is the net velocity of electrons (drift velocity) considered to be zero, before setting up any electric field? I mean in the derivation of the equation drift velocity: $$ v =-\frac{Eet}{m} $$
3
votes
0answers
43 views

Partition function of classical quadrupole in an electric field

The partition function of a dipole in an electric field is a well-known problem, analytical solvable (nice integral, can be calculated with pen and paper), for example in the Langevin treatment of ...
15
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2answers
1k views

Why is there no Gravitational Magnetic Field?

We think that the electric field and gravitational field operate similarly with their corresponding charges/masses. With just a difference that the electric field is sometimes attractive and sometimes ...
1
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1answer
78 views

Calculating equipotential lines and current density in a rectangular conductor

(This isn't homework, I'm trying to make an illustration for an article I'm writing.) Let's say that I have a thin rectangular bar of uniform conductivity, and I have point probes at various places: ...