Tagged Questions
4
votes
1answer
60 views
How much negative charge do I accumulate by touching the earth?
The Earth carries a negative electric charge of roughly 500 thousand Coulombs (according to different sources I've seen). If I touch the Earth I should therefore pick up some of this electric charge ...
5
votes
2answers
168 views
Is there a momentum for charge?
Since mass and charge behave similarly, so, just like center of mass, I define a point center of charge, that is defined by
$$\vec r_{qm} = \frac {\sum{q_i \vec r_i}} {\sum{q_i}}$$
where $\vec r_i$ ...
0
votes
1answer
43 views
What types of materials can be electrically charged by rubbing?
What types of materials can be electrically charged by rubbing? Is there a certain type of materials in which static electricity can be produced by rubbing together two different materials?
0
votes
2answers
77 views
Definition of electric charge and proper explanation
Is there a definition of electric charge and proper explanation of it?
It is said "Electric charge is the physical property of matter that causes it to experience a force when close to other ...
0
votes
0answers
30 views
Energy content after moving point charge [closed]
I have the following exercise:
In point A there is a charge with $Q_1 = 3.3\times10^{-5} C$
In point B charge $Q_2 = 8.5\times10^{-6} C$
In point C charge $Q_3 = -6\times10^{-6} C$
This happens ...
0
votes
2answers
43 views
About the electrostatic voltage
What's the difference between electrostatic voltage and normal voltage, like the battery's voltage.
How to calculate the charge on a charged plate if we knew its electrostatic voltage?
1
vote
1answer
53 views
Induced charge on sphere
I have a conducting sphere ($radius = a$) at potential $V_0$. It is enclosed by another thin shell ($radius = b, b > a$) which has a charge density $\sigma (\theta) = \sigma_0 \cos(\theta)$ for the ...
0
votes
1answer
78 views
Electrostatic Potential Energy Calculation (Sign Problem)
In the derivation of electrostatic potential energy ,
how is $ds=-dr$ step justified ?
Why we use a differential position vector ? Why doesn't directly work and potential energy give the correct ...
1
vote
0answers
40 views
Static electrical attraction [closed]
Coulomb's law is used to calculate the electrical attraction between 2 charged particles, what formula do I use to calculate an electrical attraction magnitude between 2 plates? Let's assume the first ...
5
votes
1answer
219 views
How can I prevent my son building up static on his trampoline?
Whenever my three year old son plays on his trampoline, it doesn't take very long for him to start building up a significant amount of static electricity. His hair stands on end (which is quite ...
3
votes
1answer
91 views
Make water droplets charged?
Normally water molecules are electrically neutral.
But I have seen somewhere ideas about electric energy generators mentioning that water droplets might be used in some applications as they are ...
0
votes
1answer
62 views
Find the dielectric constant of the medium?
Two point charges a distance $d$ apart in free space exert a force of $1.4\times10^{-4}N$. When the free space is replaced by a homogeneous dielectric medium, the force becomes $0.9\times10^{-4}N$. ...
2
votes
3answers
108 views
Is electron velocity at induction higher than in a wire?
When looking to the electrostatic induction on a microscopic level, do the electrons really move with high velocities or they move like when a current passes through the wire (slowly).
1
vote
1answer
144 views
Parallel capacitors without battery. Does charge flowing after a dielectric input?
If I charge two capacitors which are connected parallel $[$the minus (-) of the one opposite to the minus (-) of the other and the plus(+) of the one opposite to the plus (+) of the other.$]$, will I ...
0
votes
0answers
37 views
Charge residing on an overpolished surface
I had very well read that when charge is stored on a rough surface, the leakage is very high from the pointed tips of such surfaces, by a phenomenon called action of points. But now, I've come to know ...
0
votes
1answer
116 views
Why doesn't a gaussian surface pass through discrete charges?
I have read that Gaussian surface cannot pass through discrete charges. Why is it so?
I have even seen in application of Gauss' Law when we imagine a Gaussian Surface passing through a charge ...
1
vote
1answer
65 views
Electrostatic induction
Is this a correct definition of electrostatic induction, The production of opposite charges on a neutral body when a charged body is brought near to it? I think it's not the production but ...
0
votes
1answer
72 views
Electric field of a negative charge
Displacing something against the gravitational field, gains it potential energy. Moving something against the nature requires work. If the electric field of a negative source charge 'Q' points inward, ...
2
votes
2answers
216 views
Electric field of a negative charge
How was it discovered that the electric field of a negative charge points towards the charge itself? Is it true?
(Courtesy of wikipedia)
0
votes
1answer
60 views
Electrostatic potential and charge
Say we have a balloon, negatively charged, the voltage on it is 500 V. Can I measure the charge on it or in other words, the number of excess electrons?
0
votes
1answer
63 views
Electric charge and the distance
The strength of an electric field is: $E = 200\ \mathrm{N/C}$
The potential (of the test charge) is: $V = 600\ \mathrm{V}$
$\epsilon_r=1$
I need to calculate the distance between this point and the ...
0
votes
1answer
106 views
How to positively charge an object with a power source? [duplicate]
How do you positively charge something consistently? By what mechanism could this be achieved?
2
votes
3answers
128 views
Explanation on the resulting forces of two positive point charges
Why will the resulting force lines of two positive point charges be like this:
I would expect this:
2
votes
4answers
163 views
How does positive charge spread out in conductors?
I know that when there are excess positive charges in a conductor, for example, a metal sphere, the positive charges will spread out over its surface. However, I am confused about how this excess ...
1
vote
3answers
195 views
Why can we use Gauss' law to compute electric field?
For simplicity I'm considering only the sphere case.
In the Gauss' Law formulation we have some field E introduced by charges $Q$ inside some sphere, then we compute flux and integrate, and we get ...
1
vote
1answer
35 views
Permanently charging a sphere by induction using a high voltage
I want to charge a sphere using a van de graff generator , it would sound easy , but using a 1 MV or a 900 KV is really hard, it is enough to break like 1 meter of air so whenever i try to ground the ...
2
votes
1answer
68 views
Electrostatic charge leakage
What are the ways electrostatic charged objects leak charge in humid conditions?
Can airborne particles pick up charge by contact, then be repelled hence removing charge? If so would it be a ...
0
votes
1answer
192 views
Electric Fields
The problem I am working on is, "In the figure below, determine the point (other than infinity) at which the electric field is zero. (Let $q_1 = -2.45\ \mu C$ and $q_2 = 6.5\ \mu C$)
Here is a little ...
3
votes
1answer
369 views
Electric Field due to a charged sphere
Suppose we have a spherical surface with a surface charge density varying as $cos(\theta)$. Apparently one can find the electric field both outside and inside such a spherical surface by superposing ...
0
votes
2answers
105 views
Is there a limit to the charge of a body?
Can a body be limitlessly charged? Suppose a sphere of radius $R$. Can it be charged limitlessly?
0
votes
1answer
32 views
Are the ions in a fluorescent lamps concentrated near the electrodes?
Are the ions in a fluorescent lamps concentrated near the electrodes , and just the electrons move to the other electrode or the positive mercury ions move too?
5
votes
1answer
547 views
What defines the maximum charge a capacitor can store?
The formula for a capacitor discharging is $Q=Q_0e^{-\frac{t}{RC}}$
Where $Q_0$ is the maximum charge. But what property defines the maximum charge a capacitor can store?
If it depends on ...
1
vote
1answer
266 views
( Legendre Generating Function) Off axis Electric Potential from an insulated disk
An insulated disk, uniform surface charge density $\sigma$, of radius $R$ is laid on the $x,y$ plane. Deduce the electric potential $V(z)$ along the z-axis. Next consider an off axis point $p'$, ...
1
vote
2answers
209 views
Change in intensity of electric field with constant velocity
Consider a +Q charged particle is travelling towards another test charge +Q. Now what would be the difference in electric field experienced by the test charge(avoid the gradual decrease in distance ...
0
votes
1answer
49 views
Charging using a CRT TV set
I was doing an experiment with my CRT TV where I put aluminum foil on the screen wire it to a can and open the TV and a ring between 2 can will swing if I ground the other can. ...
0
votes
1answer
157 views
Charge on capacitor plates in series combination?
Suppose 2 capacitors are connected in series, the plates connected to the battery terminals receive charges $+q$ and $-q$, and the isolated plates in the combination receive equal and opposite charges ...
0
votes
1answer
119 views
About voltage and charge of van de graff generator
I have read that in case of Van de graff generator $V=kQ/r$ where $r$ is radius of the sphere.
If that's the case, does the same voltage results in bigger charges in bigger radii?
3
votes
2answers
269 views
Conservation of Charge and Method of Images
Consider the typical problem, "You have a conducting sphere of charge $Q$ and a point charge q a certain distance away, what is the force on the point charge?". The solution is a simple application of ...
2
votes
3answers
281 views
Delta Dirac Charge Density question
I have to write an expression for the charge density $\rho(\vec{r})$ of a point charge $q$ at $\vec{r}^{\prime}$, ensuring that the volume integral equals $q$.
The only place any charge exists is at ...
0
votes
1answer
98 views
Will I recieve a shock if I charged a capacitor then i touch the 2 poles in same time?
What happens if I charged a capacitor then i touch the 2 poles in same time?
0
votes
1answer
47 views
Can we transfer the charge on a plate of a capacitor elsewhere?
I know it is hard , but can we transfer the charge on a capacitor plate elsewhere?
0
votes
0answers
113 views
Charging a metal plate
I am supposed to find a way to charge a metal plate with a defined charge ( in nanocoulomb) and it must have a + charge so basically i want to know if this way is correct and applicable, and if there ...
0
votes
0answers
74 views
What happens when I bring a sphere of positive charge near to the sphere of negative charge?
I am wondering what would be the charge density distribution when I bring a sphere of positive charge $Q$ near to the sphere of negative charge? What would be the charge distribution inside the sphere ...
0
votes
1answer
47 views
Charge of an electrolytic capacitors
I can't understand the electrolytic capacitors, when a capacitor has a capacitance of 100 microfarads, does that mean that when it is charged with 100 volts will the charge of the plate be 0.01 ...
0
votes
0answers
58 views
Is there a minimum charge for the electroscope to work? [closed]
I built an electroscope, and I noticed that some charged objects didn't have enough charge to show any interaction.
So i was wondering if there is a threshold minimum charge for the electroscope to ...
0
votes
1answer
131 views
Can high charges (like $1\times 10^{-3}$ coulomb) be acheived?
How can we charge a metal electrode with large charges ? When i saw a video about measuring a charge using a visiostat on a balloon , the charge was 0.6 nano-coulomb. Is the charge of 1 coulomb ...
0
votes
2answers
2k views
Why is electric field zero inside a hollow metal sphere ?
The figure below shows a hollow metal sphere with a positive point charge $Q$ sitting outside it. What is the electric field at the center of sphere ? The answer is zero (look at here at the beginning ...
1
vote
2answers
212 views
Find the quantity of charge - given potential function
A potential function is given by $V(r)=\frac{Ae^{-\lambda r}}{r}$ Find charge density and hence charge.
I first took the gradient of potential to get $\vec{E}(r)=\frac{Ae^{-\lambda ...
0
votes
1answer
243 views
Simple quadrupole moment
I have a very simple problem: There is a charge $-q$ at $(0, 0, d)$ and $(0, 0, -d)$ as well a charge $2q$ at $(0, 0, 0)$. I have to calculate the quadrupole moment using spherical coordinates. I use ...
0
votes
2answers
150 views
Effect of charges near a parallel plate capacitor
If I charged a parallel plate capacitor. And then, I insert a charged body near one of the plates.
Will there be any interactions like attraction or repulsion?
What if I disconnected the battery?
