Elecricity Definition and 101 Threads

Homework Statement A distribution of charge with spherical symmetry has volumetric density given by: $$ \rho(r) = \rho_0 e^{ \frac {-r} {a} }, \left( 0 \leq r < \infty \right); $$ where ##\rho_0## and ##a## is constant. a) Find the total charge b) Find ##\vec E## in an arbitrary point...

Hello! new here. recently I've developed an interest in the way electricity is produced, I've seen some mechanisms, most of them are steam turbine based. i have a few questions about the topic, mainly about thermodynamics. if i want to create enough energy to move a steam turbine that requires...

HiI was reading about capacitors and potential energy. But the equation seems counter to how i thought. For potential energy you have: U = Q^2 / 2C or U = CV^2 / 2 But doesn't this suggest you lose potential energy the more capacitance you have? Since in the first equation as C increases U...

[ mentor note: post adjusted to conform to homework template and some spellings fixed ] 1. The Problem I have some few questions that connect voltage, current and resistance. Imagine that we have a circuit that consists of a battery (5V), 2 resistors. Now once we close the circuit, battery...

I'm considering two identical spherical conductor each of radius ##a## and separated by a distance ##d##, and trying to figure out the capacitance of this configuration. My thoughts are that since capacitance is $$C=\frac {Q}{V}$$ and that the spherical conductors are equipotential surfaces...

I'd like to start a thread of thoughts and opinions of a topic that I am considering spending time and money on. Unfortunately, I do not have a very broad knowledge of the engineering intricacies of the topic. I'm really curious if there has been a proposal or workings of a vehicle that uses an...

I'm working on a project and came across electromagnetic braking recently and I'm really curious to know if it's really feasible. The project in brief is a vehicle on a monorail at speeds of +600km/hr needs to be stopped. The monorail is made of an alloy of aluminium. I have no background in...

Homework Statement 1. A 2.01 uFcapacitor that is initially uncharged is connected in series with a 6.51 kΩ resistor and an emf source with 74.6 V and negligible internal resistance. The circuit is completed at t = 0. b) At what value of t is the rate at which electrical energy is being...

Homework Statement Please help me answer thew question in the image.[/B] Homework Equations Current Density J=conductivity X Electric field[/B] The Attempt at a Solution As the current density depends on the conductivity of the material through which the electrons constitutuing it are...

I've seen answers saying that electricity takes path of least resistance, I know this and there is no need to explain this for me. A forum's answer told me that the electrons initially flow through to the path with resistance and eventually becomes congested (redirecting the remaining electrons...

I am reading a proof for this statement and I don't understand one of the steps. It is stated that since the surrounding medium is nonconductive the flow of charge at the surface has no component along the normal of the surface. From this the conclusion is drawn that the E field along the normal...

Homework Statement There are two metallic spheres, of same kind ,separeted from one another .One of them has charge 6 C wheras the another one is neutral.They are brought in contact for a long time.Then they are separeted again.Now what is the charges of the spheres?Homework Equations ...

My basic understanding of a dielectric material is that the coulomb force between charges in a dielectric must be reduced by some factor since some of the electric field energy gets stored in the medium. The following thought experiment is confusing me and I am wondering where my mistake lies...

Homework Statement https://www.bpho.org.uk/user/pages/05.past-papers/06.as-challenge/_general/BPhO_AS_2010_QP.pdf 12. A combination of resistors shown below represents a pair of transmission lines with a fault in the insulation between them. The wires have a uniform resistance, but do not have...

I was recently solving a problem that involved a circuit with a capacitor that was connected to a battery at one end(the second plate just had a wire which didnt lead anywhere). In the solutions it said that this capacitor cannot have any charge since there is no path for the current to flow...

If a beam of electrons starts to accelerate from rest due to a uniform electric field in vacuum will the electrons feel any mutual repulsion or attraction? Will the beam first expand then contract? If yes, how does this happen? This was a question under magnetism head.

Hello I know that maxwells equations are consistent with relativity. The following thought experiment seems to imply otherwise so I am wondering where my mistake lies. Lets say we have some very large conductor loop(with a radius of many lightyears). At the center of the loop is some magnet...

I have learned about the electric fields of static charges and those of moving charges. From what I gather(although I have not really learned the specifics) when charges are accelerated they emit electromagntic waves which are essentialy an electromagnetic field progagating through space. My...

I have a plate capacitor with a given charge. It is then dipped in a dielectric fluid and I must determine which height the fluid reaches(all the necessary parameters are given). I can solve this problem if I make the following assumption: the polarization of the dielectric does not( or...

Homework Statement A plane electromagnetic wave travels upward. At t = 0, x = 0, its electric field has the value E = 5 V/m and points eastward. What is the wave's magnetic field at t = 0, x = 0? Homework Equations B=B init. sin(kx-wt) E=E inti. sin(kx-wt) E=cB The Attempt at a Solution I am...

Hello, I'm boy who suddenly been strucked by curiosity on how hand crank generator works and i watch and read some of how to create one, specially this one on youtube: and i want to create one but i don't have a 3D printer, but i saw some alternative but as i do/design my own coil based on...

1. Homework Statement Hello, I'm learning electricity and I'm having a few conceptual questions regarding the subject ( especially about neutral objects ) which I'm unsure of the answers and I'd be happy if someone could help me:1. Is the charge density of a neutral object ( doesn't matter if...

When an object with a net charge is connected to the ground by some conducting material the net charge disappears. The only answer I was able to find was that the net charge gets spread out, which will clearly cause it to become negligible. What causes this to happen?

Hi, I'm sorry if this question's been asked before but I was wondering how hands-on electrical engineering can be. Are there jobs where an EE can find themselves doing designing and getting to work with their hands? I find the theoretical stuff interesting as well as the more hands-on work.

Homework Statement Find the admissible current density Jadm for a wire that has no insulation and also for a wire that has two layers of insulation and compare it to Jadm for the case when the wire has only one layer of insulation.2. The attempt at a solution and equations In the image I've...

I know that the equation F = CQ1Q2/r^2 can be rearranged to give electric field measured in volts per meter and then arearranged to get voltage but I don’t thing the answers I get are correct. I once got 10^9 volts between 2 coulombs 2 meters apart? I am really confused please help.

I'm having trouble understanding how voltage drops. My understanding of voltage is a difference in potential, with potential being how much work is necessary to move a test charge to a specific orientation. So, if we have a circuit with say, a 12V battery and a 1 ohm resistor, and I had a +1...

Hello everyone, First off, i would like to apologize for any spelling errors. I am Portuguese and my english is going to be very simple. I am in the process of building something and i am reaching out to the physics community for help solving a problem. I am a CNC programmer and while i was in...

I can help students on electrical and electronic related chapter doubts.

Hi, I have some confusion about the jump conditions for an electric field across an interface between two materials with different properties. In general, we have the two jump conditions across an interface: n.(ɛE)+ - n.(ɛE)- = σ...

Homework Statement A neutral atom with known polarizability α is located at the origin. A point charge Q is situated on the y-axis a large distance d from the atom. (The atom therefore becomes polarized due to the electric field of the point charge.) (a) Find the electric field due to the atom...

Homework Statement https://imgur.com/3H3pCkD R is the resistance of each resistor, determine total resistance in the circuit. (see the image in the link above) Homework Equations R=1/R₁+1/R₂+1/R₃+... (in parralel circuit) R=R₁+R₂+R₃... (in series circuit)The Attempt at a Solution I'm...

Homework Statement suppose a coil is placed in a changing magnetic field and the circuit is not closed will the current induce in the coil Homework EquationsThe Attempt at a Solution What I thought was that the current flows only in a closed circuit because it needs a potential difference...

*This is a question in an assignment that i have to submit. 1. Homework Statement Two imaginary spherical surfaces of radius (R) and (2R) respectively surround a positive point charge (Q) located at the center of the concentric spheres. What is the number of electric field lines (N2) going...

<< Thread moved from a technical forum, so no HH Template is shown >> Our teacher gave us a lab, and we have to write a procedure on how to test the electrical conductivity of multiple substances. However, on the materials, all that was written was "electrical conductivity tester", which I'm...

For starters, it’s like 11 pm and I just had to ask this question so please bear with me if what I’m asking is confusing. So my question is what is electricity made out of. Atom wise. I know I probably could’ve Googled this but I figured why not ask this for everyone’s benefit. I figured hey...

Homework Statement What is the relationship of charge polarity and voltage polarity? I understand an anion has negative charge and cation ion has negative charge, but does an anion have a positive voltage and the cation have a negative voltage? Given the above is generally true, when is the...

Homework Statement There are 2 circuits. A: -A series circuit Components: -Motor -Filament lamp -Resistor B: -A parallel circuit Components: -Motor -Filament lamp -Resistor -Each component is in a separate parallel circuit Question)Explain why the power of the motor is lower in the circuit...

Homework Statement A hollow conducting sphere has inner radius R and outer radius 1.5R. A +40nC point charge is placed at the center. What is the total charge on the interior and exterior walls of the sphere? R=10cm Homework Equations Gauss's Law σ = Qenc/A The Attempt at a Solution I'm not...

Hi ! I want to do research and publish a research paper on a topic related to physics . I am an undergraduate student , but I am much interested in research work. Kindly suggest me a topic on which I should do research ? And how much time will it take for the complete my research work ?

Homework Statement S stands for load and G for a generator. There is an odd term used- power flux distribution in the schematic. That`s what needs to be found. Homework EquationsThe Attempt at a Solution

Hi, so I was hoping to get an EE's explanation for what just happened. So my son was apparently over by the light switch pointing a UV pen light at the switch. Suddenly there was very loud, gunshot-like pop, sparks flew, and I had to go reset the breaker. Maybe correlation doesn't imply...

Homework Statement There is a conductor with the square-shaped area. the Radii are r1 , r2 with width b and resistivity ## \rho_R##. Find the resistance R between A and B 2. Homework Equations ##I = \iint_A\vec J \cdot d \vec A## ## \vec J = \kappa \vec E ## ## \vec E = \rho \vec J## ## V =...

Hello, I was thinking that using AC to supply power to a lamp would cause it to flicker, considering that the potential difference keeps changing signs. This would mean that the current supplies voltage to the lamp, only to take it back after a really small amount of time. Voltage say's...

Consider a parallel plate capacitor formed by two plates of length ##L## and width ##d##, separated by a distance ##e##. There is a vacuum in between the plates. Let's note the capacitance of this arrangement ##C_0##. I insert a conducting plate of length ##l=L/2##, with ##D##, and thickness...

Homework Statement Two sinusoidal voltages with amplitude 15Volts and frequency 2,771Hz are separated in time by 68% of a period. What is the phase shift in degrees between the two signals?Homework Equations y= Asin(omega)(x-h) The Attempt at a Solution I know my A is 15 and I'm pretty sure...

Just a couple of simple questions. 1-Why does electricity kill? 2-What causes a magnet to be a magnet and certain things magnetic?

Homework Statement Ok this isn't particularly homework, but just revision needed. I tried asking the teacher but he's making no sense whatsoever. So, Firstly: 1. So here is my very badly drawn diagram. A very simple circuit with an LED...

Hello, Thank you very much for takign the time to help me out. This is an applied calculus 3 (multivariable calc) level problem. I have an answer, but it is nonsensical as the units are not in accordance with units of charge, C. Homework Statement Instructions: Use Gauss' Law for...

Can someone please check my answers here, there are loads of formulaes been give that I haven't used so I'm not sure if they are right or not, thanks.