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 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...
Would i assume that fg = fm (force gravity holding straight wire down is equal to the magnetic force) and isolate for I?
Help if you're available please!
TL;DR Summary: Find the electric field of a long line charge at a radial distance where the potential is 24V higher than at a radial distance r_1=3m where E=4V/m. Answer: 29.5V/m.
Never mind: I retract this question. The integral apparently is supposed to diverge! I apologize for not reading...
For this problem,
If we assume that x = 0 is where the spring connects to the wall, then the rest position of the mass-spring-electric field position is x = EQ/k and the max position is x = 2EQ/k. Is there a reason for the symmetry between the rest position and max position? (The symmetry...
For this problem,
The solution is,
However, why can the differential area not be:
I tried integrating and got,
Can someone please tell me what I have done wrong?
Thank you!
A self-balancing electric unicycle consists of a frame+pedals that the rider stands on, a motor where the stator is attached to the frame+pedals, and a rotor which is attached to the wheel+tire.
An EUC is similar to an inverted pendulum: the EUC frame is free to rotate about its axis, limited...
There are small 15kw electric motors <$500*.
LiFePO4 batteries that offer 60kwh** weigh <50kilograms, cost <$500, take as much space as the gas used to take.
The hood could be removed or replaced with extra seats or used for cargo.
Ultra-lightweight 3D printed magnesium bodies*** should be...
For this part(b) of this problem, how is the magnitude of the total electric force zero?
I thought it would be:
If they asked for the total electric force, then I would have said zero because the two electric force vectors cancel.
Many thanks!
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!
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...
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...
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...
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...