Electricity Definition and 999 Threads

Electrochemical hydrogen compressors (https://en.wikipedia.org/wiki/Electrochemical_hydrogen_compressor) basically convert an electrical potential difference into a pressure difference. Would it be possible to run one of these in reverse, i.e. using a pressure difference to create a voltage? If...

Hi PhysicsForums, I'm asking this as part of a small research project of mine in exploring hydrogen as an alternative energy source to fossil fuels. Based on my limited understanding, hydrogen is a good alternative to fossil fuels (especially in cars) because the only waste product is water...

How electricity passing through a conductor produces magnetic field around it. How an induction motor works. The energy or electricity which passes trough green earthing wire is transmitted into the ground. Why this energy is not conserved and can be used in future. All these three things are...

I read somewhere that conductors don't really store charge? How can this be correct? When a conductor is charged by conduction, the electrons spread throughout the surface of the conductor. Doesn't this mean that the capacitor is storing this electricity? What prevents conductors from being...

Found this interesting video - thought there would be interest here... VIDEO LINK

Hello, I have a bit of an issue and can't figure out how to find out the answer. I want to understand how to find out what battery I would need if I want to scrap the diesel generator I have and go for a battery bank. I have a 1250 kVA rated generator. PF is 0.85, Rated voltage is 400V, rated...

Homework Statement Hi everyone. I was reading through a book and came across the following question and explanation: " You are given two 200 meter strands of identical copper wire. With one strand you create a coil whose radius is 2 cm. With the second strand you create a 4 cm coil. Assuming...

Good Afternoon everyone, Question: What are some effective ways to generate a high voltage (Multiple KV) using amateur equipment? I've dealt with high voltage before, so I'm aware of the safety issues. Anyway, here is what I've got thus far: If you go on ebay, and search for high voltage power...

If your axel in you car was magnetic with copper wire casing would that produce electricity? If so how much? If there is no resistance in that process then there wouldn't be a detrimental effect on the performance (bar added weight of the wire) With the raising popularity of electric cars it...

as far as I know this is real, from Scotland. could be a good discussion starter for static electricity;

Hi, I realized I didn't understand the physical model of something I know the theory of pretty well. I was considering the real power loss of an AC transmission line I2*R, then I realized that from source to load the electrons in an AC line don't actually move anywhere. (as far as I know) Yet if...

My dad is working on a project where he intends to convert mechanical into electrical energy, and he was wondering if a particular magnet and coil configuration works for electricity generation. And if it does, how are the voltage and current calculated. Lets say: The coils have a diameter of...

Homework Statement Is it possible to introduce local charge on a conductor? Homework Equations - The Attempt at a Solution I know that electrons can move freely from atom to atom in the conductor, so if you introduce excess electrons to the conductor, they'll spread out and there won't be a...

Homework Statement Two identical light bulbs are connected to the ends of the battery. In the first case they are connected in series and in the second they are connected in parallel mode. What is the ratio of the electrical power of light bulbs connected as mentioned? Homework Equations...

Homework Statement The average wavelength that LED emits is 500nm. The electrical power of the LED is 300mW and the efficiency of turning energy into light is 66%. Number of emitted photons in unit time is? Homework Equations ##E_f=hcf## ##\frac{Pt}{E_f}=number of photons## The Attempt at a...

Hi guys! I am currently having Physics Internal Assessment in my school and I want to do an experiment to calculate the different times it takes for a 9V cell to to discharge (reach a 0.1V) in different temperatures. The problem I am having right now is to efficiently discharge my cell. How can...

Homework Statement Ammeter shows 1.2 A and 1.0 A. How large amount of charge passing through the lamp in 1 minute? https://physicsforums-bernhardtmediall.netdna-ssl.com/data/attachments/84/84982-6e293679b3592fb475f0f9cac697526f.jpg Homework Equations Q=I*t[/B] The Attempt at a Solution I =...

can anybody tell me how to transfer tension energy into electricity, new project i am doing is to do with, if the force of rain can be transferred somehow using a tensioned material. (like a solar panel) and if so is it possible to actually create energy off of this and turn it into electricity...

I'm having trouble understanding the effect of efficiency on the cost of electricity for a PV system. By the graph I've uploaded, as the efficiency of a PV system goes up, the cost of electricity goes up. But the equation in the other photo has efficiency in the denominator of the equation...

Hello everyone and thank you for your replies in advance. I am currently doing a physics project where I am testing to see how the number of coils of wire effects the current generated when a magnet is run through the coil. I am currently just dropping the magnet through the coil from a constant...

Hello. I am an occasional poster here with little background but a big interest in the mental experiments (ME) of Einstein and others. Of particular interest to me are factors related to what I call the Classic Spaceship Mental Experiment. [mentor's note: a link to an unacceptable reference...

Hi I was wondering if there is a way to produce energy using the movement of vehicles on the road. I do not know which principles can come into picture, but I believe Electromagnetism/ detection is the way to go? If someone could at least throw me in the right direction of which field to...

If I took a charged particle and accelerated it, that acceleration would have an effect on charges potentials, allowing for the radiation of electromagnetic waves. This acceleration would be local to a point in spacetime and the observed potentials would depend on the frame of reference of the...

A (possibly stupid) static electricity question: Person A is carrying an electrostatic charge. They touch person B, both get a shock. If both persons were off the ground(eg hanging from ropes) ...would they still get a shock?

In classical physics, when electric charges accelerate, they are expected to radiate. Electromagnetic waves, are by their nature the result of changing electric and magnetic fields. But is it possible to have acceleration of charges without having changing electric and magnetic fields? One...

So in conductors, the electrons will distribute themselves to the surface via repulsion forces. But why do we say that the electric field inside is zero? If I put a positive charge inside, clearly it will move in some direction from the electric field of generated from the electrons. Also, are...

Homework Statement I picked a nuclear power plant. I spent a bit of time researching what the basic process is and that's what I've arrived at so far. I'm not certain if the answer is complete/decent, it seems like a very complex process which even for 'point form' could be a page of...

When I am calculating the power in the circuit , do I use the RMS values , or the peak values and why ?

Homework Statement A moving particle encounters an external electric field that decreases its kinetic energy from 9480 eV to 8260 eV as the particle moves from position A to position B. The electric potential atA is -43.0 V, and that at B is +25.0 V. Determine the charge of the particle...

Please help! I have recently completed an experiment on transformers, using a step up transformer. I am aware of all the theory that shows that in a step up transformer, the induced voltage should increase and the induced current should decrease. However, in my experiment, my hypothesis is not...

So from Faraday's law, a change in the magnetic flux will induce an emf on a loop of wire. { \phi }_{ B }\quad =\quad BA\\ { \varepsilon }_{ ind }\quad =\quad \frac { d{ \phi }_{ B } }{ dt } (in this case a perpendicular field) From these equations, it looks like the only way to induce a...

Homework Statement In the following figure, R1= 3.1 Ω, R2= 4.9 Ω, L1= 0.155 H, L2= 0.2 H and the ideal battery has ε = 5.6 V. Just after switch S is closed, at what rate is the current in inductor 1 changing? Homework Equations { \varepsilon }_{ induced }\quad =\quad L\frac { di }{ dt } \\...

How come the magnetic field outside a solenoid is practically zero? I've read reasons along the lines of: -The magnetic field cancels out on the outside. Of course the net force cancels out, but what if you have an object placed on just one spot? The force on that object clearly is not 0...

Hi people! I am a high school rising senior who is looking to self study electricity and magnetism over the summer. Particularly, my aim is to take the ap physics c electricity and magnetism exam as a result of this self study but also to realize if I want to work with hardware/electrical...

Can someone please help me out with this practice test and provide explanations?

Homework Statement **Question** Is the magnetic field directed into the page or out of the page?Homework Equations Right Hand Rule The Attempt at a Solution My index finger is pointing downwards, and since the magnetic force is towards the right and this is an electron (negative) my thumb...

If photons are part of a magnetic field like electrons, which electrons can be read with an amp meter, what can measure or count photons? Electrons are not counted but the magnetic field changes when more current flows and the ammeter reads a change in the magnetic field. What type of light are...

Homework Statement The figure shows two very long straight wires (in cross section) that each carry a current of 3.19 A directly out of the page. Distance d1 = 6.00 m and distance d2 = 4.00 m. What is the magnitude of the net magnetic field at point P, which lies on a perpendicular bisector to...

To start with this is not a numerical but merely a basic concept I fail to understand. I will quote what the CIE book says "Consider a battery of emf 3 V and of internal resistacne 1 ohm. The maximum current that can be drawn from this battery is I=e/r = 3/1=3 A The terminal p.d of the battery...

The light in a lightbulb is the result of an increase in temperature. This increase is created by both a highter elektrical resistance in the wire and a highter elektric current. But a higher resistance results in a lower elektric current (I) (I=V/R), so it is both increasing and decreasing the...

Homework Statement A thin insulating rod with charge density lambda=+5nC/m is arranged inside a thin conducting cylindrical shell of radius r =3 cm. The rod and the shell are on the same axis, and infinite in length. What is electric field at point p? 6cm from the central axis. Homework...

Homework Statement Homework Equations Cost = rate x energy consumption (kWh) Energy consumption = power (kW) x total time (hrs) The Attempt at a Solution so here are my answers, can someone please verify if these are correct, thanks! a) To calculate power: There are fifteen 100 W...

Homework Statement The cell in the circuit has an emf of 2.0 V. When the variable resistor has a resistance of 4.0 Ω, the potential difference (pd) across the terminals of the cell is 1.0 V. What is the pd across the terminals of the cell when the resistance of the variable resistor is 12...

We know that objects like plastic become negative (with rubbing) but what will happen if we rub plastic and plastic, one of them will become positive which one ?

We have a solar tracking device that uses phase change of paraffin wax when heated inside a solar receiver. With a helical slot in a torque tube we can translate the expansion into rotational motion. We use this rotation to point solar panels at the sun, thus generating more electricity. Look...

Here is the rub. Most of the online sources and in a kind of statement in my book says that we gain a negative charge when we rub our feet on the carpet. So when we touch a door knob we get a electric shock because the electrons is transferred from us to the door knob However, Shouldn't it be...

Homework Statement A wire is moved with constant velocity such that the motion is perpendicular to the length of the wire in a region containing magnetic field perpendicular to the plane of motion. The wire has a resistance R. Will thermel energy be generated in the wire? Homework Equations...

My professor says resistance depends on, R\quad =\quad \frac { \rho L }{ A } And is defined as, R\quad =\quad \frac { V }{ I } What does she mean? What is the difference? A definition is denoted by \equiv, what is the difference between that and an ordinary equal sign?

Homework Statement A circular rod has a radius of curvature R = 8.11 cm, and a uniformly distributed positive charge Q = 6.25 pC and subtends an angle theta = 2.40 rad. What is the magnitude of the electric field that Q produces at the center of curvature? Homework Equations E = kQ/r^2 6.25 pC...

Homework Statement A charged particle (either an electron or a proton) is moving rightward between two parallel charged plates separated by distance d=2.87mm. The plate potentials are V1=-75.8V and V2=-49V. The particle is slowing from an initial speed of 90.0 km/s at the left plate. What is...