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.
I'm having an exam soon so i want to make sure. Is the electric field here zero?? cause if i draw gauss surface covering both of them they should cancel out or am i wrong.
I know that inside region 1, the D-field is zero as it is a conducting sphere, the E-field must be zero. It makes sense that in region 2 (inside the dielectric) there is a D-field.
My question is, is there a D-field outside the dielectric material (r>R)? Obviously there will be an E-field, but...
If a electrically charged mass travels thru a magnetic(m) field, it will accelerate at right angles to its velocity and the m-field. Under some conditions like this the charged mass will travel in a circular loop due to this magnetic force acceleration. This info is all over the internet. e.g...
Greetings everyone
I work at a company that sells chargers for electric vehicles and I’m working on the electrical projects.
The chargers I work with, are alternating current (AC) and the main mode here is a three-phase installation 220 V, at 7.04 kW with a current of 32 amps.
If the system...
I believe I have all parameters set up correctly to evaluate part A of this problem but I am unsure of the bounds.
I can't integrate from 0 to R because that part of this sheet has a hole there. I need to integrate from R to the other end of the sheet.
Im not sure how I would figure out the...
I wanted to post my work so far to see if I am on the right path toward the correct answer so far.
I have attached a ss of the actual problem and my work in the attachments
Im having trouble understanding the wording to this problem. When it says "from r=0 to r=infinity". My Qenc would zero out. I guess it makes sense that from infinitely far away you wouldn't "feel' the electric field but considering this question leads to 4 other questions I don't think I am...
I've calculated the intensity for every point charge which are
EA = 6.741 x 10¹³ NC¯¹
EB = 4.494 x 10¹¹ NC¯¹
EC = 6.741 x 10¹³ NC¯¹
and I am pretty sure about this far but I am struggling to calculate the X-axis intensity and Y-axis intensity to find the entire approximate intensity with the...
I encountered a problem regarding the appropriate sign needed to be taken for the work done on a dipole when it rotates in a uniform electric field and would appreciate some help.
The torque on a dipole can be defined as
τ=PEsinθ
The work done on a dipole to move it from an angle ##\theta_0##...
Hi. A electromagnetic wave consists of an electric and a magnetic component. I believe that the electric field strength is measured in volts per meter. The magnetic field I think is measured in Tesla. Let's imagine that I measure the electic field strength of two different radio stations and...
Hi,
We know that a varying magnetic field creates and induced electric field, and a varying electric field creates an induced magnetic field.
If there is a varying electric field (let's say sinusoidal), then this electric field creates an induced magnetic field. And if this produced magnetic...
According to theory I should be able to get the Electric Field (E) from its pOtential (V) by doing the grad (V) so
E = -grad(V), however, V is contant V = k*lambda* pi which results having E =0, but this is not right. What I am missing??
see figure below
The answer should be Ex = 2*k*lambda / r...
From the second equation I get that,
##\vec D =\frac{q}{4\pi \vec r^2}\hat r##
From first equation I get that
##\vec E = \frac{q}{4\pi \vec r^2 \epsilon}=\frac{q}{4\pi \vec r^2 K \epsilon_0}##
But I saw that the answer is ##\vec E=\frac{\vec E_0}{K}##
While writing the comment my mind said...
The dielectric strength of air (ie the maximum electric field that the material can withstand under ideal conditions without undergoing electrical breakdown and becoming electrically conductive) is 3 000 kV ( https://en.wikipedia.org/wiki/Dielectric_strength#Break_down_field_strength ).
In...
While reading about electromagnetism from the OpenStax books with my son (and doing some experiments), he asked this question.
Suppose I hang a pendulum and make it oscillate inside a coil connected to a Galvanometer as shown in the schematic diagram:
Hopefully the image is clear enough. His...
So I have been given a uniform electric field ##\vec{E}=20 V/m## in the direction as show in the image. I have been told to calculate the potential difference ##VC - VA##. According to the teacher (on YouTube) the potential difference ##VC - VA = -10\sqrt{2}V##. But I say it's ##-20 V## as...
My general understanding of electric flux density is 'electric flux per unit area'. This gives the SI unit N/C. But According the formula of electric flux density, D=eplison*E, the SI unit is C/m^2. How come the dimension in both cases not matching if both are true?
I have read three definitions of electric flux in textbook which is confusing me..
1. Electric flux is the number of electric lines passing through any area of a surface.
2. Electric flux is the number of electric lines passing through unit area per second held perpendicularly.
3. Electric flux...
Electric Flux = E*A = 5*6(0.05)^2.
when i look up at other sources they use Electric flux = q/ (8.854*10^-12 [this is e]) equation
but I am confused on why the E*A equation don't work. The answer is 0.02Nm^2/C
As shown in figure below, the electric field E will be normal to the cylinder's cross sectional A
even for distant points since the charge is distributed evenly all over the charged surface and also the surface is very large resulting in a symmetry. So the derived formula should also apply to...
Hi all!
I was wondering,
Is it possible, given a specific dipolar molecule, to create the perfect oscillating electric field so as to heat it and not, i.e. the water around it?
What I'm basically asking is could there exist a specific microwave just for X and not all dipolar molecules without...
I am having some problems involving the force that a source moving with speed v along the x-axis would exert on a test charge at the x axis.
Moving to the frame of the source charge, we got that the electric field it exerts is $$E' = kq/x'²$$
Now, moving back to the lab frame, and considering...
Picture: Energy source => LR Oscillator => Transformer => Transmission line => Electric dipole antenna => traveling wave
Why would the charge even oscillate in the antenna as opposed to building up in the antenna? The transmission line + antenna is not a closed circuit right?
A thin shell in reality doesn't have zero thickness. Consider the image below, showing a cross-section of a small portion of the shell:
Here we are considering a more general case in which we have electric fields of magnitude ##E_1## and ##E_2## on each side of the shell.
Gauss's Law...
What am I missing?
I also don't get the title of the section: "Charge distributions with enough symmetry for Gauss's Law".
I thought Gauss's Law was valid for any closed surface enclosing a charge. I don't understand what "enough symmetry" means in the title above. I get that with symmetry...
Using Gauss's Law
By using a symmetry argument, we expect the magnitude of the electric field to be constant on planes parallel to the non-conducting plane.
We need to choose a Gaussian surface. A straightforward one is a cylinder, ie a "Gaussian pillbox".
The charge enclosed is...
I am interested in particular in the second integral, in the ##\hat{r}## direction.
Here is my depiction of the problem:
As far as I can tell, due to the symmetry of the problem, this integral should be zero.
$$\int_0^R \frac{r^2}{(x^2+r^2)^{3/2}}dr\hat{r}$$
I don't believe I need to...
The strategy will be to figure out what ##dq##, ##\hat{r}_{dq,p}##, and ##r_{dq,p}## are, plug them into the expression for ##d\vec{E}_{p_r}##, then integrate over ##d\vec{E}_{p_r}## to obtain ##\vec{E}_{p_r}##, the electric field at ##P## due to the arc on the right.
Then I will repeat the...
I read that a kg of gas provides about 13kWh (47.5MJ) of energy and that burning a kg of gas emits about 3.15 kg of CO2. So presumably a gas-powered engine emits 3.15/13 or about .242kg of CO2 per kWh of work, right?
According to the EIA, the US electric grid emits about 0.85lb or 0.386kg of...
Hi all,
I have a doubt when calculating the electric field of a uniformly polarized cylinder P along its longest axis. The cylinder has length L and radius a.
Using Gauss's law:
$$\int D\cdot ds = \rho_{f} =0 \, \, (eq .1)$$
The electric field inside of cylinder would be: $$E =-...
The net Electric field(inside the dielectric):
$$E_{net} = \frac{1}{4\pi \varepsilon_0 \varepsilon_r} \frac{q}{r^2}$$
$$\vec E_{net} = \vec E_{applied} - \vec p$$
where p is the polarization vector.
let charge ##q_{-}## be present on the inner surface of dielectric and ##q_{+}## on the outer...
Hi folks,
I'm searching for information/procedure and also calculations/equations on how to correctly wind a stator on a (general or DC 3-phase) brushless motor? I.e. how to wind a copper wire X number of times around the stators, and thus get the desired performance/force that is required...
Hello, any answers appreciated:
'Two spheres are 5 m apart. Sphere 1 has a charge of -20 mC and sphere two has a charge of -50 mC. (a) Find the strength of the electric field at the sphere's halfway point. (b) Find the electric potential at the halfway point
Okay so this is how it looks like,and there are the given values;
a) I've tried it like this. So I now this formula $$ E = \frac{J}{\sigma} $$ where sigma is the conductivity value. Now to get E we need this formula;
$$ U = \int_{l}{} E \ ds ] $$ Now to get U we can use the ## U = \frac{P}{I}...
Hello. I am having some trouble to understand the resolution of this question.
We could easily try to calculate the electric field relative resultant at the screen. The problem i am having is about the amplitude of the electric field:
Generally, we have that the intensity part dependent of the...
hi guys
our instructor asked us to try to graph the projection of the electric field intensity at a certain point p(x,y) , for two charges q+-q located
at (-a,0) , (a,0), Now starting with the equation
$$\frac{dy}{dx} = \frac{E_{y}}{E_{x}}$$
after transforming this equation I got...
Hello! I am susposed to find the force of q3.The problem is given as in the picture ;
Now we are given a hint,and it says the following:
"First calculate the forces of the individual charges on q3. The superposition principle says that you can then simply add these forces vectorially
to get...
I'm preparing for exam but it seems I can't find problems similar to this on the internet.
Here I will apply Gauss's law on the electric field vector to get the charge density. but the problem is that I can't find similar examples on the internet that uses direct vectors on Maxwell's equations...
So I started with b)
and it there was no q2 this would seem reasonable
I was wanted to ask , what effect does q2 have on potential of these two charges? Because it has to be given for a reason.
My approach is thus: the shell will have induced charges if it's conducting resulting in E at the centre of shell(though flux at centre will be 0). For non conducting spheres there can be no induction only polarization of dipoles, therefore the E field at centre will remain 0. Is my approach...