Electricity Definition and 999 Threads

Homework Statement A force eld E has the spherical components Er = (2Dcosθ)/r3 Eθ = (Dsinθ)/r3 E\phi = 0: (a) Evaluate by line integration the work it does in taking a point (parti- cle) from point A in the diagram to point B via the quarter circle r = a; 0 <...

Separate question. Can anyone tell me what the limitations would be of trying to convert the planet's ever increasing heat into electricity. I'm imagining building materials that could take 100-120 degree heat and convert it for use in running home appliances, including air conditioners. How...

So I'm a physics major in my second semester of undergrad physics and have been completely blown away by electricity and magnetism. The stuff just amazes me. So I was wondering what the current hot topics of E&M are. What are the unanswered questions? What kind of things would I be...

Homework Statement The ac circuit has 3 components in series: a Capacitor C=120μF, an Inductor L=100mH, and a resistor R=7Ω. A) Find the amplitude of the voltage across the resistor R in the LCR circuit below, when operated at a frequency of 45 Hz? B) What is the phase difference...

Hello, I have started reading a beginners book (from the "stop faking it" series) on electricity and magnetism. Its supplied with funny little experiments to help me understand the topic. But I have trouble understanding the intimate relationship between electricity and magnetism. I believe I...

So, I don't want to disclose why I want to know about this because its to do with a friends invention and it would be unfair to publish too much information without his consent. That's my disclosure so to speak. I'm interested in how static electricity is managed in vehicles. I remember...

Greetings PFers I’m thinking about building a Tiny House similar to the one below, except outfitted with solar power. http://www.tumbleweedhouses.com/products/weebee/#ad-image-0 A Tiny house is a small (~120 sqft) home on a trailer bed. I’m interested in designing one that is equipped with a...

I am sure this is a set of naieve question first of all. However i'd appreciate someone taking the time to enlighten me, as my mind is boggled by this and has been for some days now. I have watched numerous videos on the subject of electricity but am still somewhat confused. My issue is taking...

hey everyone, I have a questions, that is very general, and perhaps, silly... but why are coils so significant in terms of electricity and magnetic fields? why is it when you push a magnet through a coil, you get a charge, but not when you touch it to a straight copper pipe? Or when you see...

As technology has advanced, we have come up with ways to produce and use more energy, and have come up with many different ways of doing so. Most of what I know of using energy for households or factories or big machines is that they use electricity, as a way to convert fuel, heat, wind...

Is there a way to harness electricity from a steel ball bearing moving through a magnetic field? The ball would be heavy enough to move through the entire magnetic field (downhill) from end to end without being caught in the magnetic field. Would having 2 copper rails supporting the ball...

Hello, I am required to write a feasibility study for my Technical English course about a project that could be done in my field of study, I'm an Electrical and Computer Engineering major and I thought of the idea of converting the heat produced by friction of chalk on classroom boards, feet...

I know that pure water doesn't conduct electricity well, and that adding an electrolyte generally increases conductivity. However, does there come a point where increasing the concentration of electrolytes actually DECREASES conductivity?

Hi! I have been told that despite the different temperature between the surface and the Earth is different we can't use it to produce electricity by using the laws of thermodynamics .. shy isn't possible ?

Homework Statement Given an electric field ε V/m that is constant in the x-direction and a charge +q C located at the origin and free to move in the x-direction. (a) What is the magnitude and direction of the force F acting on q? (b) If q moves under the influence of F a distance d m, how...

Can someone recommend a physics book on electricity and magnetism? The book that I just finished reading for my class was https://www.amazon.com/dp/0971313458/?tag=pfamazon01-20 The book above hardley mentioned vectors and I am looking for a book that explains all the concepts in terms of...

Homework Statement Homework Equations The Attempt at a Solution i chose positive and negative but i am not sure.

I am building a scale model wind farm with 10 Brushless DC motors. Each motor is rated 12v and 1.3 amps. Provided that I can generate 12 V on each motor, what is a realistic amount of power that I can generate? Thank you.

Hi,can you please help to understand why is the potential difference the same across the gap between the plates of both capacitors connected in parallel?

Is it real? how does it work?

0:30 "So if I have a magnetic field that's increasing increasing increasing" I'm probably taking this too literal, but the magnetic field coming from the neo magnet isn't increasing or decreasing. The gentleman is only moving the magnetic field (the magnet) in closer proximity to the coil, so...

Hi everybody! I'm currently working on a project where a wet cooling tower is involved. The wet cooling tower is an induced draft system. I know the volume of air handled and also the properties of the air entering and leaving the system. I want to determine the electricity consumption of...

Just have a question: how can I make a steady temperature to heat water or liquid where I have 5 volts with 2 or 3 grounds as a source only? Please explain the things that can be required to increase things such as resistance and current and their source such diodes or batteries with the...

Hello guys, I have a few questions to ask and I really need an answer for them all. Firstly, I know that the Dynamo or the Generator produces electricity to the vehicle engines and houses, etc... But I seriously want to know how Dynamos produce electricity exactly. I didn't understood exactly...

Hello, I have few questions about batteries and AC->DC adapters 1- in AC-DC converter: if I have a device required 12v and 1amp .. will it hurt the circuit if I connect 12v but more amps ? I heard it draw only required currents .. is that true ? 2- in batteries: why when we buy...

Hello, so today i was thinking about alternative ways to provide electricity to a motor in a fixed wing aircraft. Ideas: 1. Use thermoelectrics. They would generate the most voltage around the engine, so maybe they would only be placed here, or all over the aircraft. Advantage: unlike solar...

If a prerequisite for E&M is Multivariable calculus, why is it offered in high school (without that pre-req)? Is the High School E&M equivalent to physics 2 in college, and if that is so, Physics 2 is still offered before Multivariate calculus. Can someone clear this up for me. Am I getting two...

I'm trying to run electricity from one side of the my land (country side) to the other. Electricity is 2000 feet away from light pole. first 500 feet I'm running number 8 wire. for the other 1500 I'm running number 12 wire. I'm getting a power drop because of distance. Local electricians told me...

Hi, Can anyone take a look at this article and tell me your opinion? I want to know if this is true or not before learning it? http://science.uniserve.edu.au/school/curric/stage6/phys/stw2002/sefton.pdf

What possible rate of electricity would be generated if a 10,000 lb weight goes down a 30 degree inclined track, attached by a cable that spins the rotor in a generator mounted at the top of the track? Please assume that friction on the track is minimal and that there is a large supply of these...

[FONT="Arial"]Dear Physicists I am well aware that this question does not have all the necessary information on order to get an exact answer, but what I am hoping to find is some educated guesses backed by some math. Lets imagine a 50 MT Pot filled with magma that is 700 C hot. Let’s imagine...

I'm just wondering if there are more efficient ways of generating electricity from fuel sources such as lpg and kerosene that are more efficient than thermophotovoltaics, thermoelectrics, and heat engines like stirling & steam. Would it be a fuel cell such as this? Also, what type of fuel...

So I am taking Physics II this fall semester. I am an engineering major, and I am currently split between mechanical, and civil. My questions is how hard will the class be for me? I have already done the three semesters of calculus including a vector calculus extension. I got an A in calc III...

Hello Dear Fellows! We all know that light is an electromagnetic wave and also we know that an antenna receives EM waves and convert it into electrical energy. My question is that is it possible for any specially design antenna to receive Light as a source of EM waves...

I have a question about the equation for work as it pertains to electrostatics and electricity. One book I read says equation for work done by electric field is W=qV, but another book says W=-PE. However, when I try both equations for the following problem I get different answer. Could someone...

Homework Statement A proton of mass 1.67 * 10^-27 kg moves from a location where V1 = 75 V to a spot where Vf = -20V. a) Calculate the change in the protons kinetic energy b) Replace the proton with an electron, determine its change in kinetic energy Homework Equations The...

Homework Statement The potential at a point is 20 V. Calculate the work done in bringing a charge of 0.5 C to this point. Homework Equations V = Ee / q W = -Ee The Attempt at a Solution Ee = 10 J W = -10 J But the answer is 10 J. Why isn't it negative? It's contradicting...

A) I want to understand electricity in terms of quantum theory. as I understand photons are the carriers of EM energy so how do photons trasfer energy from electric company or battery through a wire. and the connection to electron movement (do electrons from one atom bum into another...

Why don't fluorescent bulbs blow up when electricity is connected? My understanding is that gas inside heats up to plasma to make light. Wouldn't the heat of plasma expand the gas, add extra pressure and the pressure would break the glass? Maybe super low pressure inside the bulb to start with?

"Everything there is in the universe is a number of conductors that their overall load is greater than zero. Prove that there is at least one conductor with no negative density surface charge anywhere" thx for any help...

Hello, Ok, this may be a stupid one, I'm not a scientist nor engineer, but it's been haunting me since, due to some conjuncture, it came into my mind. Sorry if this is not the right category for this topic. I attached very rough sketches about this. A very summary description: 1. Any kind of...

Homework Statement 2)The power stations providing electricity for the National Grid generate electricity at 25kV. The typical demand on an average winter's day in the north-west of England is 6000MW. The current output form the generators is 240kV. Transformers raise the transmission voltage...

Hello, I was wondering if anyone could tell me of an easily available (to a primary school teacher) solid material that conducts electricity, but noticeably poorly, so that it can be demonstrated and hopefully performed by 9 year olds. To be exact, I want a solid material that can be...

Can someone give me explanations for the answers to these questions as the book just gives small simple answers? 1)A volume of 1.2x10^-5 m^3 of conducting paint is poured into a glass cylinder of base area 3.0x10^-4 m^2. It fills the cylinder to a height of 40mm. The resistance between the top...

We have noticed in various electricity pylons/towers that groundwire or shieldwire is always placed at the top and between the two conductors ? why is that so? If you look at the 220kV structures or 500kV structures of pylons, you will notice the groundwire is placed at the middle of...

In the Electricity section of the AQA A Level Physics data sheet (link given bellow) it includes these 3 equations: http://store.aqa.org.uk/qual/gce/pdf/AQA-PHYA4-PHYA5-W-A2-DFB.PDF V=W/Q Emf = E/Q Emf = I(R+r) I understand that Emf and Voltage both have the unit Volts, and Work Done...

https://www.dropbox.com/s/gvml20bk7435zoa/a.gif I need to calculate the equivalent capacitance of this circuit, but I cannot tell which of the capacitors are in series or in parallel. Can someone explain to me how can we figure this out?

I was wondering out of boredom, how much would a generator last generating electricity if I keep it running for forever. Assuming I have fuel for forever and I start a generator, how much would it last before it stops generating electricity? Like, does the copper wires wear out and stop...

In the top circuit, electricity doesn't flow through section 2, but it does in section 1. In the bottom circuit however, electricity flows through both sections 3 and 4. Why does simply adding a resistor stop the flow of electricity in 2? Much appreciated!

I watched a documentary recently about electricity generation, and I've been trying to figure out whether an example they provided is actually possible or not in theory. If a big wheel, much like a Ferris wheel, spins but slowly, very slowly (let's say 5 revolutions per minute), and you...