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Questions tagged [electrostatics]

Electrostatics is concerned with the electrical fields and scalar potentials of stationary electrical charges and charge distributions. Use this for questions about electromagnetic situations in which currents and magnetic fields are absent, otherwise use [tag:electromagnetism] and/or [tag:magnetic-...

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field of electricity

A small object carrying a charge of —55.0 μC experiences a downward force of 6.20 X 10-9 N when placed at a certain point in an electric field. a) What are the magnitude and direction of the electric ...
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Electric field Calculations

The electric field due to an infinite line of charge is perpendicular to the line and has magnitude $E=\frac{2}{\lambda r}$. Consider an imaginary cylinder with radius $r= 0.250\ \text{m}$ and length$...
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Potential difference that is established between parallel plates in air [on hold]

A potential difference of 4.75 kV is established between parallel plates in air. a.) If the air becomes electrically conducting when the electric field exceeds 3.00×10 power of 6 v/m, what is the ...
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How to determine change in potential energy with respect to (E) from parallel to perpendicular?

The ammonia molecule (NH3) has a dipole moment of 5.0x10^30 C•m. Ammonia molecules in the gas phase are placed in a uniform electric field (E) with magnitude 1.6x10^6 N/C. How do I solve for the ...
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Electric charge [on hold]

In a physics lecture demonstration in a charge of -0.180 uC is placed on the spherical dome should you sit for the electric field at your location to be within the recommended maximum of 614 N/C. ...
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Contains Voltages and conductors [on hold]

Can someone help me solve this physics problem? I'm having trouble understanding in our physics lesson and I'm confused on what is being asked here. And i'm also confused on what will happen to the ...
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If the plates of a capacitor have different areas, do the charges on the two plates have equal magnitudes?

May I ask for you kind heart to help me with this discussion question? Suppose the two plates of a capacitor have different areas. When the capacitor is charged by connecting it to a battery, do ...
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2answers
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Hanging two charged sphere by a light string

NB: This is not a homework question. I am not searching for any solution of a math problem. I found something incorrect to do always in the nature of two charged pith balls hanging from a light ...
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Electrostatic potential of a charged sphere [on hold]

A total electric charge of 3.50nC is distributed uniformly over the surface of a metal sphere with a radius of 24.0cm. If the potential is zero at a point at infinity, find the value of the potential ...
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Can lightning bend metal?

If lightning strikes a metal pole, will it bend because of the force exerted by Earth's magnetic field on the current?
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What is the potential inside the cavity and within the material of a conductor? [on hold]

A conductor that carries a net charge Q has a hollow, empty cavity in its interior. Does the potential vary from point to point within the material of the conductor? What about within the cavity? How ...
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Change in electric potential energy and absolute temperature [on hold]

The ammonia molecule (NH3) has a dipole moment of 5.0x10^30 C•m. Ammonia molecules in the gas phase are placed in a uniform electric field (E) with magnitude 1.6x10^6 N/C. (a) What is the change in ...
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Electro-magnetic field __ [on hold]

Each square centimeter of the surface of an infinite plane sheet of paper has 2.50 x 106 excess electrons. What is the magnitude and direction of the electric field if it is 5.00 cm from the surface ...
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ELECTRIC FIELD AND ELECTRIC FORCES [on hold]

a.) What must be the charge (sign and magnitude) of a 1.45g particle for it to remain stationary when placed in a downward-directed electric field of magnitude 650N/C? b.) What is the magnitude of ...
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Phenomenon called ”St. Elmo’s fire” [on hold]

When a thunderstorm is approaching, sailors at sea sometimes observe a phenomenon called ”St. Elmo’s fire”, a bluish flickering light at the tips of masts. What causes this? Why does it occur at the ...
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1answer
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Electric force is stronger than gravitational force yet gravitational forces holds the Sun and planets in their orbits around the Sun [on hold]

The electric force between an electron and a proton, between two electrons, or between two protons is much stronger than the gravitational force between any of these pairs of particles. Yet even ...
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If positive particle Q is held at a fixed point, and a second particle is fired at it [on hold]

If positive particle Q is held at a fixed point, and a second positive particle is fired at it. Would the angular momentum of the second particle constant? Why or why not?
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Electric field (magnitude and direction) [on hold]

The question is already in the picture attached ma'am/sir. Thank you very much!
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Find the magnitude of the electric field and the speed of the proton when it strikes the negatively charged plate [on hold]

A uniform electric field exists in the region between two oppositely charged plane parallel plates. A proton is released from rest at the surface of the positively charged plate strikes the surface of ...
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Solving the Distance in Electric Potential [on hold]

A potential charge has a charge of 2.50 x 〖10〗^(-11) C. At what distance at the point charge is the electric potential a.) 90.0 V? b.) 30.0 V? Take the potential to be zero at an infinite distance ...
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1answer
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Conducting sphere

A conducting sphere is to be charged by bringing in positive charge a little at a time until the total charge is $Q$. The total work required for this process is alleged to be proportional to $Q$ ...
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1answer
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Two point charges

Is it possible to have an arrangement of two point charges separated by a finite distance such that the electrical potential energy of the arrangement is the same as if the two charges were infinitely ...
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1answer
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Grounded parallel plate capacitor

What will be the charge distribution if a parallel plate capacitor, which is not connected to any battery, is given charge on one plate(say Q on the left plate) and is grounded on the outer side of ...
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1answer
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How do I determine the accuracy of this two-dimensional potential field?

Let's say I want to solve this problem. I know the values on the boundaries and I guess an initial solution on the rectangular grid inside these boundaries, see figure below. Potential=10 on ...
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2answers
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Potential energy is zero at infinite distance

We set the electrical potential energy to be zero in infinite distance to calculate potential energy at a distance $r$. But how is it possible from infinite distance to end up with finite distance? ...
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1answer
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Capacitor with a spring [on hold]

The plates of capacitor are attached with non conducting spring of spring constant k. The initial separation between the plates is d and the spring is relaxed initially. Now the charges +Q and -Q is ...
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Finding the electric field generated by a charge in cubic torus space(three-torus)

Imagine you are in a cubic torus space(three-torus) where if you go far enough in one direction you come back to where you started. Now imagine you have a charge in this space. Due to the geometry of ...
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1answer
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Why does charge 'stick' to the Gaussian surface?

I'm currently studying Gauss's Law and interaction of the charge with different Gaussian surfaces etc. But here's something that I couldn't understand. Why does a charge 'stick' to a Gaussian surface? ...
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Deriving the electric displacement field ($D$ field)

I am trying to derive the $D$ field (or electric displacement field): $$D=\varepsilon _{0}E+P$$ I am using the following relationships: $$\rho=\rho_{f} + \rho_{b}$$ $$ \rho_{b} =-\nabla \cdot P$$ ...
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1answer
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Functions unbounded at a point on the domain: How to show electric field exists for any continuous volume charge density?

My understanding after reading Mike Stone's answer: \begin{align} \vec{E} &= k \iiint_{V} \dfrac{\rho(x',y',z')[x-x'\hat{(i)}+y-y'\hat{(j)}+z-z'\hat{(k)}]}{[(x-x')^{2}+(y-y')^{2}+(z-z')^{2}]^{...
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1answer
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The direction of the electric field at a point on a diameter away from the center of a uniformly (positively) charged hemisphere

The answer is : perpendicular to the diameter. I don't understand how to arrive at that answer. I'm taking a high school physics course and have covered Electric field and Gauss's law for simple ...
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1answer
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Electrostatic Energy [duplicate]

We all know that electrostatic PE between 2 point charges is kq1×q2/r.But what is PE between a hollow uniformly charged sphere of radius R and charge Q ??
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1answer
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Griffiths Multipole Expansion and $Q$ going to zero

Griffiths states that given the multipole expansion: $$V(\vec{r})=\frac{1}{4\pi\epsilon_o}\sum_{n=0}^\infty\frac{1}{r^{(n+1)}}\int(\vec{r}')^nP_n(cos(\theta')\rho(\vec{r}')d\tau'$$ for large $r$ the ...
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1answer
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Dielectrics and capacitors

Does the electric field after passing through the dielectric reduce. What I mean is If there is a dielectric which is in between the plates ( but NOT IN contact with them ) Suppose field begins from ...
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1answer
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Electric force between two parallel plates one of which got a rough surface

So if I have two parallel metal sheets separated by 0.1 meters with air as a dielectric with a breakdown strength of 3MV/m and I'm applying a voltage pulse that goes from 0 to 100kV in few ...
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2answers
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Electric field of infinite sheet

I have a question regarding the electric field of an infinite sheet in the $x-y$-plane at $z=0$ with a constant sheet charge density $\sigma$. There are many ways to obtain the result $$\boldsymbol E=\...
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Question on force between dipoles [closed]

Two point dipoles of dipole moment $p_1$ and $p_2$ are at a distance $x$ from each other, and $p_1$ is parallel to $p_2$. The force between the dipoles is? I’m not understanding what does point ...
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Firing an electron towards a proton

Suppose I have an electron and a proton. If i fired the electron towards the proton, due to the attraction between them the path of the electron will change. How should I shoot the electron so that it ...
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Why do salts form ions?

For example, sodium chloride is formed because a chlorine atom "takes" one electron from a sodium atom, thus forming a sodium+ and a chlorine- ion which stick together because of their different ...
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Question regarding electric flux distribution in an asymmetrical body

I have a question about how flux will be divided in asymmetric shapes. I encountered this on a test where you have to find the flux through a surface (given below). I placed a symmetric cuboid on the ...
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Delectricity in a Plate capacitor

My class has been doing an experiment with Plate capacitors, to prove the proportionality of the formula $C=\epsilon_0\epsilon_r A/d$ (looking at $A$ and $d$). We changed the distance, $d$, by ...
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1answer
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Electric field due to a square sheet, missing by a factor of 2, need insight

So the problem is asking me to find the Electric field a height z above the center of a square sheet of side a I approach the problem a different way than the book, I derive the electric field due to ...
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1answer
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Grounding and equipotential lines

In my textbook it says: One of the rules for static electric fields and conductors is that the electric field must be perpendicular to the surface of any conductor. This implies that a conductor is ...
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2answers
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Does Coulomb's law hold as long as $\dot{\rho} = 0$?

Does Coulomb's law, $$\textbf{E}\left(\textbf{r}\right) = \frac{1}{4\pi\epsilon_0}\int \rho\left(\textbf{r}'\right)\frac{\textbf{r} - \textbf{r}'}{\left|\textbf{r} - \textbf{r}'\right|^3}dV',$$ hold ...
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Field between 2 electrodes experiment

We were asked to conduct an experiment that is as follows: Connect 4.5V constant voltage across 2 electrodes of thin Cu wire, dipped in a tub of copper sulfate solution. A needle is connected to a ...
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Field of a charge inside a spherical shell

Let's for now assume that we have a charge $Q$ at the origin inside of a conducting shell. This means that we have an electric field $$\vec E_1(\vec r)=\begin{cases}\frac{Q}{4\pi\varepsilon_0}\cdot\...
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Electric field produced by oscillating charge

In Feynman Lectures on Physics, Volume 1, Chapter 29 he proves that electric field propagates like a wave. My attempt is like this:- I don't know latex therefore I'm posting the image But to prove ...
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1answer
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Electrostatic force per unit area on a hemisphere due to its other half

From Griffiths, intro to electrodyanmics: Now, I approach the problem a different way then he does, and I miss the answer by a factor of half The way I do it is that I find the electric field ...
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2answers
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Rutherford gold experiment

When an alpha particle is nearing the gold atoms nucleus, it is slowing down due to electrostatic repulsion, right? But then why is the acceleration or velocity not a minimum at that point (the ...
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1answer
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Computing the Electric Field of a Weirdly Shaped Wire

The typical examples presented when computing electric (vector) fields are uniformly charged straight wires and semicircles, and they actually do not compute the entire vector field, but simply the ...