Electric Definition and 1000 Threads

Since this quesstion popped up in this thread I thought it might be better to create a new thread: https://www.physicsforums.com/threads/a-question-about-an-electrons-movement-in-a-dc-circuit.997736/ The question is the following: What kind of descriptive model could/should one use while first...

Solving for the volume and surface bound charge densities was easy using equations 1) and 2). The polarization only has an r component so ##ρ_b=-\frac 1 {r^2} \frac {d} {dr} (r^2 \vec P)=-α(n+2)r^{n-1}##, and ##\hat n=\hat r## so ##σ_b=αa^n##. To find ##\vec E## I intend to use equation 3)...

i have drawn the E field as below, hence the F will be in the upward direction for electron a. Using energy is constant, the velocity ##v_x## as it crosses A is ##0.5mv_x^2 = q*V_a## ##v_x = \sqrt{(\frac{2qV_a} m)} m/s## one doubt i have here is, the question mentions electrons, but i have...

Why was that concept necessary ?, I know there's also a gravitational equivalent of this concept I couldn't find anything on google Thanks Daniel

I'm trying to solve this, but i don't really know how to start this problem. There are two line charges and i must find the E. Field on the center.

Like an electric field is applying a sort of force on a particle. I was wondering if this at all impacts the potential energy of a particle. For instance, when the force of gravity does work on an object, its potential energy changes as a consequence. Would it be the same thing here?

So I am converting an old gas lawn tractor to electric. I have a 48v 2000w motor to drive the axle. For the deck, I sourced two 40v old Ryobi deck motors (I don't have them yet). Since my power supply will be a 48v lithium battery, I wanted to run the two deck motors off the controller running...

There is a section in the BJT explanation the charge density and the corresponding electric field graphs. But i was not sure how the electric field is derived and hence i started deriving it. Please correct me if my understanding is wrong in posting the question It is an ##npn## BJT. My...

Here's an image. O and O' are the respective centers, a is the distance between them, r is the distance from the center of the sphere to P, and r' = r - a, the distance from O' to P. The approach (which I don't understnad) given is to use Gauss' Law and superposition, so that we calculate the...

here is the situation Hi guys, I should illustrate the motion of an electron in both cases, but I cannot really understand how will the field be like in the gap between the two(filled) hemispheres(conductor and non). Another thing is: for the conductive hemispheres, does it make any sense to...

The Poynting vector $$\vec S=\frac{1}{\mu_0} \vec E \times \vec B$$ gives the power per unit area. If I need this in terms of electric field only,I should be able to write B=E/c (for EM wave) Assuming they're perpendicular, ##S =\frac{1}{\mu_0 c}E^2##. Now, ##c=\frac{1}{\sqrt{\mu_0 \epsilon_0}}...

I am trying to calculate the power calculation of a general circuit with voltage leading the current by a phase difference of ##\theta##. The instantaneous voltage is given by ##v = V_m\sin(\omega t +\theta) ; i = I_m\sin(\omega t) ##. The instantaneous power is then ##p = V_m I_m \sin(\omega t...

Hi guys, In my head, torque has also been associated with a bare SCALAR physical quantity given by the formula ##torque=rFsin\theta## which caused a rigid body to spin around its axis. Now, studying magnetism, I find out that torque is a VECTOR, which magnitude is indeed given by ##rFsin\theta##...

Could somebody check my solution?

Suppose I have a wire loop that I am moving away from a very long wire which carries a current upward and I want to find the induced current in the loop. The way I know how to approach this is with either Faraday's Law or motional EMF. My question concerns the motional EMF approach. My...

I figured that when you close the switch the current from the upper cell will travel through the closed switch due to it being the path of least resistance, essentially the resistor between cells is unused (was my first thought). I'm not entirely sure how to progress with this question.

Attempt at solution: a) Since I need help with b) this section can be skipped. Results : ##ρ_{psa} = -Pa ## ##ρ_{psb} = Pb ## ##ρ_{p} = \frac {-1}{R^2} \frac {∂(R^2PR)}{∂R} = -3P ## b) This is where I am unsure (first time using gauss law for P) so I need some confirmation here: ## \int...

I have to write a report about one of three motors AC type Motors, DC type Motors, Stepper Motors. I am wanting to now if anyone has any insight into which one I should talk about, which one has the most information and would be easiest to write a report on. Thanks

So, each capacitor must have a different potential difference, given by its capacity and charge... this would cause charge and current accordingly to flow in the circuit. But how do I determine the final potential difference, which would of course be the same for both of them? I have tried...

Summary:: Electric Power Systems book recommendation Hi everyone, I finished my Electrical Engineering degree 15 years ago and wanted to refresh/review/update my knowledge on Electrical Power Systems. I'm looking for a book recommendation that has: components of a power system, control of...

I'm confused at the part how 4Vc and 48 cos(60t) are deduced, that's all.

Could somebody check my solution? I want to know is it correct.

I have the problem with my solution. I don't know it is correct. Could somebody check it?

So, having two parallel resistor ##R_{1}## and ##R_{2}## , the current flowing through the equivalent one will be ##I_{eq}=I_{1}+I_{2}##. Now, it comes the point I'm not totally getting: why is ##V_{eq}=V_{1}=V_{2}##? These V's are the difference of potential measured between which points...

figure 1: → I don't understand how to approach this problem. Basically it asks for the distance r.I think I should use Gauss's law, but I've been thinking about the shape of the gaussian surface and I'm not sure about how it should look or where I should place it. Any help would be useful...

We usually think about atomic orbital as wave(function), but it was created from e.g. electron and proton approaching ~10^-10m (or much more for Rydberg atoms), and electron has associated electric field. This wavefunction also describes probability distribution for finding electron (confirmed...

My attempt at a solution is shown in attached file "work for #10.png". I used Desmos Scientific online calculator to obtain my final answer.

Specifically, I haven't really got all the "methods" through which you could calculate or derive the electric potential and in some situations, I cannot understand how and when to apply this concept. Is it something caused by any charge, or must there be an interaction between the two to...

This is not a homework question but something that bugs me a bit. My professor has stated that the electric field inside a conductor is 0. This I understand. However, he has also said that even if the conductor has some hole in it, the electric field inside this hole is also 0 Now, two...

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I am trying to understand what a point charge is. Is it just an electron? Or is it just an idea?

I tried approaching this by finding the tangential and normal electric fields. Is this the correct approach? I've attached a drawing of the surface provided. ##\oint_S E \cdot dl=0## ##E_{tan1}\Delta x-E_{tan2}\Delta x=0## We know that ##E_{tan1}=E_{tan2} Next, we can find the normal...

My first attempt revolved mostly around the solution method shown in this "site" or PowerPoint: http://physics.gmu.edu/~joe/PHYS685/Topic4.pdf . However, after studying the content and writing down my answer for the monopole moment as equal to ##\sqrt{\frac{1}{4 \pi}} \rho##, I found out the...

For the first part, since $$ E(r) \propto \frac{1}{r} \hat{r}$$ by the principle of superposition the maximal electric field should be halfway in between the two wires. Then I'm not sure how to go about the second part of the question. I understand that the total potential due to the two wires...

what I've done so far? -i've determined the vector between the point (4, 0, 0) and the point P. (4, 6, 8) - (4, 0, 0) (0, 6, 8) -The norm of this vector is the radial distance of the line to point P (the value of “ρ” in the formula) √(0^2 + 6^2 + 8^2) = 10 -> ρ = 10 -and its unit vector is...

F = qE ma = (2*10^-6) * (λ / (2pi*r*ε0) ) ma = (2*10^-6) * (4*10^-6 / (2pi*4*ε0) ) => I am not certain what to put for r ( But I sub in 4 because dist is 4) a = ( (2*10^-6) * (4*10^-6 / (2pi*4*ε0) ) )/ 0.1 a = 0.35950 v^2 = U^2 + 2 a s v = 0 u^2 = -2 a s => Can't sqrt negative so...

I seem completely lost at this. I barely know where to begin. I know that the forces will sum to 0 but the vectoral nature of the question is really confusing me. Best I have is that the distance between e and q2 has to be sqrt(2) times the distance between e and q1. I don't know where to go...

I draw the graph like this: For (b), I divided each force vector to e from p1 and p2 as x and y parts. I computed them and got Fx=-4.608*10^(-15)N Fy=-2.52*10^(-15)N However, I am not sure whether I did it correctly or not... I appreciate every help from all of you! Thank you!

Why is the divergence of an amplitude of an electric field of a monochromatic plane wave zero?

An electric car has, say, a 50 kWhr battery. 1. How much electricity, in kWhr, is needed to add 1 kWhr of stored electricity to the battery? 2. After several years, the battery capacity has, say, fallen to 25 kWhr. How much electricity, in kWhr, is now needed to add 1 kWhr of stored...

Ve=0m/s Vp= 0m/s Qe/Qp= 1.60E-19 Me=9.11E-31 Mp-1.67E-27 Ive pretty much gathered all of the equations I think I need to solve the problem. I just am stuck. The last step I realize that the forces would be equal to each other so I have mp x ap = me x ae but then when I try to solve for the...

I have these equations in my book, but I don't know how I can use them in this problem Electric field of a plane has surface electric density σ: E = σ/2εε₀ Ostrogradski - Gauss theorem: Φ₀ = integral DdS Can someone help me :((

I used the potential at the surface of the sphere for my reference point for computing the potential at a point r < R in the sphere. The potential at the surface of the sphere is ## V(R) = k \frac {Q} {R} ##. To find the potential inside the sphere, I used the Electric field inside of an...

Hi, I am interested in finding the equation for electric field equipotential lines. Ideally, it would be nice to have one equation that worked to find it for different geometries. Unfortunately, I don't think that exists. Assuming it does not exist, I think I would probably have to either solve...

Hi, I'm dealing with a more or less trivial question. Let's have a look on two situations. Consider a (negative) charged metal plate. If the plate is infinit in size it will produce a perfekt homogeneous electric field. If we now place a second plate parallel to the first one the electric...

I know that the potential of the sphere at its surface is ##V(a)=kQ/a##, and the electric field generated by it is ##E(a)=kQ/a^2##, which gives me ##V(a)=aE(a)##. When the electric field at the surface is as in the question, we have...

I would like if my procedure is correct ... Due to the symmetry of the problem, I only worry about the vertical coordinate of the field, so I will work with the magnitude of the field, and I will treat the problem in polar coordinates. ##E= \int_{R_1} ^ {R_2} \int_{0} ^ {\pi} \frac {\sigma...

Solution as stated in the problem description.

Hi! I'm a high school physics student. I really, really love physics, especially rocket science, and I had an idea about a rocket design, but I don't know how feasible it is. I was hoping you guys could give me some feedback. So I was learning about electricity, and as far as I know, electric...

I have an object that will be under DC excitation in operation but will be qualified using 60 Hz AC. Because of this, I am interested in 2 simulations. 1) I would like to simulate E-field intensity representing a 60 Hz excitation. Do I need to do a transient simulation to truly get this value...