Electricity is the set of physical phenomena associated with the presence and motion of matter that has a property of electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described by Maxwell's equations. Various common phenomena are related to electricity, including lightning, static electricity, electric heating, electric discharges and many others.
The presence of an electric charge, which can be either positive or negative, produces an electric field. The movement of electric charges is an electric current and produces a magnetic field.
When a charge is placed in a location with a non-zero electric field, a force will act on it. The magnitude of this force is given by Coulomb's law. If the charge moves, the electric field would be doing work on the electric charge. Thus we can speak of electric potential at a certain point in space, which is equal to the work done by an external agent in carrying a unit of positive charge from an arbitrarily chosen reference point to that point without any acceleration and is typically measured in volts.
Electricity is at the heart of many modern technologies, being used for:
Electric power where electric current is used to energise equipment;
Electronics which deals with electrical circuits that involve active electrical components such as vacuum tubes, transistors, diodes and integrated circuits, and associated passive interconnection technologies.Electrical phenomena have been studied since antiquity, though progress in theoretical understanding remained slow until the seventeenth and eighteenth centuries. The theory of electromagnetism was developed in the 19th century, and by the end of that century electricity was being put to industrial and residential use by electrical engineers. The rapid expansion in electrical technology at this time transformed industry and society, becoming a driving force for the Second Industrial Revolution. Electricity's extraordinary versatility means it can be put to an almost limitless set of applications which include transport, heating, lighting, communications, and computation. Electrical power is now the backbone of modern industrial society.
A recent article published in the Proceedings of the National Academy of Sciences (PNAS) describes a large electric capacitors based on carbon black and concrete. The device would be used for electric power storage - often in proximity to the electric power demand, for example, a home.
I am using an old monitor (MITSUBISHI RDT27IWLM). The power consumption changes when the screen is white or black, but does the frequency of the weak electromagnetic waves emitted from the monitor change? Or is the frequency the same, only the output is stronger/weaker?
There are two identical spheres with the same charge that are the vertices of an equilateral triangle. ##+3 \mu C## will exert an outward electric field, which is drawn in the FBD below (see the attached pic), Since the horizontal force components (1x and 2x) are equal and opposite at point P...
There are three charges with +1 μC and −1 μC, are placed at the opposite corners of a cube with edges of length 1 cm, and the distance from P to B is 1cm 2. I labeled them as A, P, and B, which is shown in the diagram below. Since we need to find the magnitude of the charge at point P and the...
How does an electric field of a moving charge, for example a moving electron, inside a wire looks like? Does it looks like this with distorted circular radial lines?
My question is specifically with calculating the intensity. The book solution is
I=P/(4*pi*r^2)
but would this not give me a weaker electrical amplitude in the final calculation after plugging it in to
I=(1/2)*√(ε0/μ0)*(E02) ?
Hi,
unfortunately, I am not sure if I have calculated the task correctly
The electric field of a point charge looks like this ##\vec{E}(\vec{r})=\frac{Q}{4 \pi \epsilon_0}\frac{\vec{r}}{|\vec{r}|^3}## I have now simply divided the electric field into its components i.e. #E_x , E-y, E_z#...
Dear Experts,
When a thin conducting sheet with no charge on is placed at a certain distance from a point charge, does it shield the electric field caused due to the point charge from reaching the other side of the sheet. As an extension of that idea, when a conducting sheet or slab is placed...
The answer is given as (a), but I think it's not correct based on the equipotential surfaces diagram given in our book for an electric dipole as below.
The red dashed lines, which are supposed to be the equipotential surfaces, are surely not representing a sphere centred at the dipole center...
If the dipole is to be in equilibrium at all positions as it's moved so that it's always inclined at 60° to the horizontal, then the torque due to electric field needs to be balanced by torque due to external forces ##F_{ext}## as shown in above diagrams. But such external forces will not make...
Apparently, we need to integrate the functions from 0 to the time when it is fully charged. However, I integrated in terms of t so the soultion (according to a graph programme) should be around 236 Vs but I don’t see how this could help me.
Electric potential = "absolute potential"
Textbooks usually connect both ends of two capacitors, of different voltages, in parallel. What would happen if we only connect one end of the capacitors? Perhaps we would have to solve for Maxwell's coefficients of potential for these two cases (to...
Hello! I have a 2 level system with a dipole moment d. I want to simulate numerically the evolution of the system under an external sinusoidal electric field (far off resonant). This is straightforward using SE. However I also have on top of that another electric field, created by a coupling of...
Griffith's E&M problem 4.7 asks to calculate the energy of a dipole in a uniform electric field and I ended up getting a different answer than the one given. I thought that calculating the energy/work done to construct the dipole is the same as dragging two point charges where one is d apart...
Quick and possibly stupid question, but in the equation for calculating the electric field:
##{\mathbf E} = \frac{1}{4πe_0}\frac{q}{r^2} \hat {\mathbf r}##
What unit is ##q## in? Coulombs?
Although now that I think more on it I suppose it also depends on the units you're using to calculate the...
Hello! I have the following Hamiltonian:
$$
\begin{pmatrix}
0 & -\Omega\sin(\omega t) \\
-\Omega\sin(\omega t) & \Delta
\end{pmatrix}
$$
where ##\Delta## is the energy splitting between the 2 levels, ##\Omega## is the Rabi frequency of the driving field and ##\omega## is the frequency of the...
Here is a depiction of the problem
a) The potential at any point P due to a charge q is given by ##\frac{kq}{r}=\frac{kq}{\lvert \vec{r}_s-\vec{r}_P \rvert}##, where ##r## is the distance from the charge to point P, which is the length of the vector difference between ##\vec{r}_s##, the...
The formula we are given is E=(1/2r)(alpha)R^2(muo)Ioe^-(alpha)t.
However, I am struggling to figure out what each of the symbols stands for in the formula...can someone help me out? Like super confused on what alpha is in this case.
I've found the distance from each point to the center, which is equal to r=20x1.732/3 = 11.55 cm.
I find out that E2 and E3 due to -4µEyC on x-direction canceled each other.
The E2y = E3Y = EY = E2Ycos60 = E2/2 = [(KQ2)/r^2]/2
So the net E-field:
E = E1 +E2y+E3Y
=kQ1/r^2 + [(KQ2)/r^2]/2 +...
Hello,
This question, which I found in various electricitiy and magnetism books (e.g. Introduction to electrodynamics grif.).
There are many variations of this question, I am mainly interested in the following setup of it:
-Suppose there is a charged disk of radius R lying in the xy-plane, and...
Question:
My answer:
What it looks like for an electric charge:
Am I correct? If you want I can hand out my Latex on how I got to it, it will refer to the book Griffiths a lot.
TL;DR Summary: A (nonconservative electric field is induced in any region in which)
A. there is a changing magnetic flux
B. there is a changing magnetic field
C. the inductive time constant is large
D. the electrical resistance is small
E. there is electrical current
there can be more than one...
Hi,
I am currently trying to do a project related to this engine and I am trying to find information about it. I am looking for technical papers, journals or overall description of the inner workings of the engine. I am looking forward for something more in depth than wikipedia.
Also...
we know that flux is equal to the area integral of electric field dotted with dA and we can set this equal to charge enclosed divided by epsilon naught. Thus, in this case, the integral simplifies to E * A = (q_enclosed)/(ε_naught) when we choose a cylindrical gaussian surface with radius of r...
For part (b),
The solution is,
However, if the acceleration was not constant during the 21 ms, then would the power required be larger?
I believe the average power required would be larger because if the train started off at a lower speed and then speed up very rapidly towards the end...
I believe this does has a couple of Calculus aspects to it but I don't really know how I'd find the surface area of inside the bowl.
The answer sheet says the answer is 252 with a margin of error of +/- 1
I only could calculate the distance travelled by each body, by making the difference between the initial and final electric potential work equal to the work of friction done by the 2 bodies.
I tried to make the kinetic energy of the first electron equal to the electric potential work.
mv^2/2=ke^2/d
We have to solve for the minimum distance between them: d=2ke^2/mv^2=5.05*10^-10 m
The force is: F=ke^2/d^2=9*10^-10 N, which is not correct.
I've figured out parts A and B but I'm struggling with Part C. I used the equation V = kQ1/r1 + kQ2/r2 where Q1 = -4.4e-12C ; k = 8.98755e9 r1 = 0.026 m Q2 = 27.4e-12 and r2 = .051-.026 My answer (8.329 V) is wrong but I have no idea why. Please help if you can.
This is a tricky and difficult question for me. I know from reading various textbooks that electric lines of force are always continuous without breaks, but cannot pinpoint a reason for this.
The only reason I can come up is that an electric line of force must always begin and end on charges...
The electric field strength at the center of a uniformly charged disk should be zero according to symmetry of concentric rings about the center, where each ring is contributing to the electric field at the center of the disk.
For a thin ring of uniform charge distribution the formula is ##E =...
Can anyone explain to me why grounded means zero electric potential. I confuse what's the relation between infinite ground conducting plane and its electric potential (the method of images).
I have a several question:
1. Why the conductor plane must be infinite, while in reality there's no...
For A.1 of this problem,
The solution is
However, I have a doubt about the linear charge density ##\lambda##.
I don't understand how ##\lambda = \frac {q}{2\pi R} ## since this is not a thin ring, but has a non-negligible width of ##2a##
I think that the toroid has a larger area than thin...
Since the electric field due to a conducting plate is twice the electric field due to a plastic plate having same charge density, the electric field at the point P will be twice in case of conducting plate and hence it is 20 volt per metre.
Is that correct?
A am working on a project that uses this 12V DC linear actuator. The actuator utilizes a magnetic coil and plunger inner design (I believe this is just a solenoid). This actuator will need to use both directions of movement for the project. In terms of wiring, what do the two female connectors...
For part (a) of this problem,
The solution is
However, my solution is
Am I correct? In the solutions that don't appear to plot the electric potential as units of ## \frac {k_eQ} {a} ## like I have which the problem statement said to do.
Many thanks!
Hello! I have 2 levels of the same parity with energies ##E_1 < E_2##, and another level of opposite parity a distance ##E## from the ##E_2##. I also have that ##E_2 - E_1 << E##. I have a laser on resonance (I am trying to scan along the resonance and find it) with the transition from ##E_2##...
For this problem,
However, I am trying to solve this problem using an alternative method compared with the solutions. My method is:
##\vec E = k_e \int \frac {dq} {r^2} \, dx ## ##\hat r##
##\vec E = k_e \int \frac {\lambda} {x^2 + d^2} \, dx## ## \hat r##
If I let ## \hat r = \frac {-x\hat i...
Hello! I have a radially pointing electric field i.e. at a given radius, R, the electric field has the same magnitude and points radially around that circle of radius R. I have a particle moving around that circle of radius R, with uniform velocity (ignore for now how it gets to move like that)...
For this problem,
The solution is,
However, should they be a vertical component of the electric field for the expression circled in red? I do understand that assuming that when the nth charge is added it is placed equal distant for the other charges so that a component of the electric field...