Electric Definition and 1000 Threads

For this problem, The solution is, However, why have they not included limits of integration? I think this is because all the small charge elements dq across the ring add up to Q. However, how would you solve this problem with limits of integration? Many thanks!

Hi! For this problem, Why is the area of each ring segment dA equal to (2π)(r)(dr)? However, according to google the area of a ring segment (Annulus) is, Many thanks!

Hi! For this problem, The solution is, However, why did they not include constants of integration in their working shown in red? Many thanks!

If I resolve the equation in 0, imposing a voltage value of 5 mV, it gives a non real solution, therefore I cannot resolve it for R=1 because I do not know which voltage value to impose. I am sure this is simpler than I am putting it :) thanks for any advice!

The picture above shows the integral that needs to be evaluated, and the associated picture ## \cos\alpha ## can be obtained via the law of cosines. I'm simply confused as to where the ##\cos\alpha ## comes from in the first place. I just don't see why ##\cos\alpha ## is necessary in this...

This is a topic that almost no one can actually explain from what I found on the internet. This answer https://physics.stackexchange.com/questions/74625/does-alternating-current-ac-require-a-complete-circuit/74999#74999 is the closest I found so far. The idea is how the grounded neutral...

Since q3=q4 and they are opposite to each others they cancel out But as soon as I try to find the electric field of one of the charges, I need the radius which is not given. By isolating the electric field for radius E=(kq)/r^2 I now have two unknowns

The electric field inside a charged spherical shell moving inertially is, per Gauss's law, zero. If the spherical shell is accelerated, the field inside is not zero anymore, but it gains a non-null component along the direction of the acceleration, as mentioned, for example, in this paper. The...

hello i would like to understand to something. here is the drew now for my question: i was able to find Ey and here is my correct answer: when i try to find Ex i didnt understand something, i found the correct answer but i need to put minus before and i want to know why? here is my solution...

Hi, I have a fairly simple question, but the answer is probably not as simple. I'm not sure to understand why in a guided wave (TE), the electric field is in the y direction. I know ##E_z = 0##, but why ##E_x = 0, B_y = 0##?

When I use Ohm's law and other related equations to calculate the heating losses in a generator I get the power output of the generator. I assume I'm using the equations wrong, and I was hoping that someone could help set me strait. I think what I would like to know is what determines the...

I know that I’m supposed to use proportional reasoning, but where does electric field even fit in? For whatever equation, I know I’m supposed to see how increasing the voltage by either 2 and 4 volts related to electric field. If electric field is the same as “U”, then wouldn’t it be...

Measured proton electromagnetic structure deviates from theoretical predictions https://www.nature.com/articles/s41586-022-05248-1Meanwhile - https://www.jlab.org/human_resources/recruiting/ELECTRON-ION COLLIDER JOB OPPORTUNITIES

Dear PF, I have a question regarding a conductor in electric filed. I have formulated my question in attached PDF file ... would please be so kind and advise me please... Thanks you in advance ...

Basically what I need is to figure out what motors I need for a design I am wanting to make for an electric motorcycle. I know that I want it to go around 60-70 mph, 60 could be the max speed if need be, for the motors to be able to move 700 lbs (which is crazy but my idea is crazy so I need it...

I have been given an electrical chain hoist to repair. The symptom is that it suddenly stopped working. I have checked the motor's windings and they each show similar DC resistance of 0.0018 ohms. I have attached the schematic (dunno why it was rotated 90 degrees during the upload). The hoist...

I am unsure of my solutions and am looking for some guidance. a.)The real part of the wave in complex notation can be written as ##\widetilde{A} = A^{i\delta}##. Writing the Complex Wave equation, we have ##\vec E(t) = \widetilde{A}e^{(-kz-\Omega t)} \hat x##. Therefore the real part is ##\vec...

I can calculate the electric field strength at any point above the plane with Gauss' Law (##E = \frac{\eta}{\varepsilon_0}##) and so the electric potential at any point a perpendicular distance ##z## above the conducting plane (##V=−\frac{\eta}{\varepsilon_0}z##). But I'm having trouble taking...

Nevermind.

If there are two charges positive and negative and their electric field point in the same direction then the total electric field would be their sum of magnitudes. Why don't we consider the sign of the charges? For example, a parallel plate capacitor is inside the region where both the positive...

Hi I have a very random question I would like to ask. Say if someone just got out the shower and either plugged something into the wall, or plugged a high voltage power cord into a device. In the process of doing so a small clump or strand of their wet hair manages to get into the socket or the...

I made a tool for calculating and visualizing how the electric and magnetic fields transform under a Lorentz boost. Thought I'd share it here, in case anyone finds it interesting. https://em-transforms.vercel.app/

Wak a ball with a bat and the ball accelerates. Now under gravity, hold the ball out horizontally, let go and the ball accelerates ... without a wak. Given that gravity arises from curved space-time, I suggest further that the acceleration of the ball arises when sub-atomic particles (in the...

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Suppose you have an infinite plane of charge. If the surface charge density is uniform, would the tangential electric force always be zero, even if it is not a conductor nor static? My thought process for this is that if you look at each point charge and draw the electric field lines, then at...

I tried gauss law. And the fact that if alpha is less than pi/2 we can say that we have two parts with angle alpha and one other part which has a normal field at the center. But non of them helped me answer. The problem's solution says that we can use the fact that our section has longitudinal...

How do you calculate the terminal velocity of the train moving in a coiled copper wire with two magnets attached to the polar ends? I have attached someone else's work I've found on the internet here and need help

We define Electric Field Intensity vector at a point as the force experienced by a unit positive charge kept at a point. Is it correct to define B vector similarly that is, is B vector the magnetic force acting on an unit magnetic north pole and is it correct to call B vector Magnetic Field...

Say we have a long solenoid with a current that is fluctuating in time. Then the changing magnetic flux in the solenoid will induce an electric field around the outside of the solenoid (Faraday's Law). This induced electric field is not conservative and therefore cannot have a corresponding...

So changing magnetic fields induce electric fields (Faraday's law when the magnetic field is changed by either moving the source or by changing the current in the source that's causing the magnetic field, ie. we're not moving the conductor where an emf is induced so there's no f=qvXB). Also...

Faraday's law tell's you about the line intergal of the electric field, but you have to know the direction of the induced electric field first in order to properly apply it. How can I find its direction? Is it in the same direction as the induced current?

Hi all. I am stuck with a seemingly silly doubt all of a sudden. The direction of Electric Field is taken from Positive to Negative (because Field Lines originate from a Positive Charge and terminate at Negative Charge). We know that direction of Dipole Moment is from Negative Charge to a...

I have a reversible electric motor that operates an automatic skylight, vintage 1985. I'm trying to figure out how it is supposed to work, but I don't recognize the rectangular gray components that are secured to the motor case with a length of plastic zip-tie. What might they be and how would...

So, I am able to calculate the electric potential in another way but I know that this way is supposed to work as well, but I don't get the correct result. I calculated the electric field at P in the previous exercise and its absolute value is $$ E = \frac {k Q} {D^2-0.25*l^2} $$ This is...

https://i.stack.imgur.com/hSOU2.png https://i.stack.imgur.com/wE2Iy.png https://i.stack.imgur.com/R7FKK.png cannot understand this deadtime compensation method. So I have provided the whole cut out of the section of this book. BOOK: Control of Electric Machine Drive Systems Book by Seung-Ki...

Assume I could produce a stream of calcium ions from a 2nm diameter nanotube by pushing them through the nanotube using coulomb repulsion. Assuming these coulomb repulsed ions produce a stream of entangled ions which then create a slowly emitting quasi static electric (near) field. Even if...

Hi. I believe I have what may be both a silly and or a weird query. In many Griffiths Problems based on Electric Field I have seen that a coordinate system other than Cartesian is being used; then using Cartesian the symmetry of the problem is worked out to deduce that the field is in (say) z...

I'm looking for a way to use these batteries that is safe and also useful. I've looked into buy inverters to turn them into portable battery packs but am out of my depth and don't want to create a device with serious potential fire hazards without thoroughly understanding the ins and outs and...

Hello everyone, This is in reference to fig 5.19 (screen shot attached - please read the paragraph which says "Figure 5.19 shows the..."). I don't get why the field outside of the sphere of radius ct acts as though the particle would have continued its motion. Author's words : "The field...

If we have an electromagnetic wave like the one in the picture and a molecule which is, in the image, the small black ball with electron cloud being the part with "minus sign" in it, does the molecule with its cloud start to oscillate, once the EM wave hits it, as an induced electric dipole...

I got E. 13q as the answer. That is what i did: The electric field due to +q at origin 0 should equal the electric fields of charges -3q and the new charge placed at 2x. So applying the equation above like this; k*(q) / (2^2) = -3q*k + (k*C)/ 4 solving for C the new charge added, gives 13q. I...

My attempt: We have 3 charges inside 2 +ve and 1 -ve so i just added them up. 4 + 5 +(-7) = 2q Then there is a -5q charge outside the sphere. I did 2q + (-5q)= -3q . The electric field flux formula is Flux= q/ E0 . So i got -3q/E0 which is obviously wrong : ) . After quick googling , I...

Is the electric field inside a sphere always 0? Even if we have charges on the surface?

I've already tried to calculate the potential with respect to the 3 segments and then apply superposition (V1+V2+V3). However, I was not very successful. My error I think is in the calculation of the radii, mainly of the line segment that is on the z axis. Can anybody help me? I need some light...

I could try to apply the Liénard-WIechert equations immediatally, but i am not sure if i understand it appropriately, so i tried to find by myself, and would like to know if you agree with me. When the information arrives in ##P##, the particle will be at ##r##, such that this condition need to...

In the statement encircled, what does Griffiths actually mean?

I have tried to solve the problem by setting as a condition that the electric field inside the conductor has to be 0, but in this way I have two unknowns (σ1 and σ2):

Does anyone know of prior work on the use of an electric fan to supply input air to a ramjet until the air speed is sufficient (~0.2 M) for normal operation? It's obviously possible, but might not be practical. The objective being the simplicity of a pulse jet without the vibration issues.

I've been researching water bridges and electrowetting to learn the effects of electric fields on water molecules but something continues to confuse me: if polar molecules can only rotate in an electric field, how is the water moving? Anyone familiar with this phenomenon? Any help is greatly...

Current drawn by motor = ##\frac{120-75}{90}## = 0.5 Amps The answer says the power output of the motor is 37.5 Watts. The only way I can get that answer is if P = IV = 0.5(75) = 37.5. This implies that in an electric motor, the back emf is the voltage of the motor. This confuses me because...