Electric energy Definition and 55 Threads

Hi, I found this interesting video about How electricity actually works. The point he makes (see for example the video at minute 7:23) is that the energy in a light bulb connected to a battery is actually transferred by the electromagnetic field and not by electrons flowing through it. The...

The following is the question and the solution to the question. I understand the solution to the part where you find the Ceq and derive Qeq from the equation Q = Ceq*V. However, I do not understand where V1 = V0-V2 come from. When calculating the minimum voltage, how do you come up with the...

While reading about electromagnetism from the OpenStax books with my son (and doing some experiments), he asked this question. Suppose I hang a pendulum and make it oscillate inside a coil connected to a Galvanometer as shown in the schematic diagram: Hopefully the image is clear enough. His...

V(ρ) = V_o*ln(ρ/0.0018)/ln(45/180) (Attached picture is where the unit vector of r is really ρ.) In cylindrical coordinates ∇V = ρ*dV/dρ + 0 + 0 ∇V =derivative[V_o*ln(ρ/0.0018)/1.386]dρ ∇V = V_o*0.0018/(1.386*ρ) E = V_o*0.0012987/ρ Work = 0.5∫∫∫εE•E dv Bounds: 0.0018 to 0.00045 m D = εE =...

Hello everyone ! I'm Hugo. I'm a french high school student. This year I've a project on new way to store electricity and their materials.I've done researches on super capacitors. But I've found only that "new way" to store electric energy. And for the material part, I don't know what I can...

Homework Statement fig 1 : Area of each plate is S, separated by 2d, charge Q in the capacitors fig 2 : uncharged conductors of area S, thickness d, inserted parallel between plates What is the ratio of electrostatic energy in fig 2 to electrostatic energy in fig 1? Homework Equations Q =...

I expect that power monitors directly measure the current, voltage change, and maybe phase to directly calculate current power use. Can electric energy directly be measured, or do meters just calculate power, and integrate it to obtain energy?

In most textbooks the electric energy is merely mentioned, not explained. From a google search the definition states that electric energy is the movement of electrons. But what exactly is it? It is obvious that it does work by transferring the potential energy to kinetic energy. So is electric...

Homework Statement Calculate the electric energy density at the surface of a 3.4 mm diameter copper wire carrying a 28 A current. Homework Equations u = (1/2) ε0 E2 The Attempt at a Solution With the electric energy density equation, I substituted in the equation for the electric field for an...

Homework Statement Calculate the electrical energy required to assemble a spherical volume of radius R and charge Q, homogeneous density ρ the answer is (3/5)Q/R the textbook says you have to build the volume integral one layer of sphere at a time, I'll get back to that later. I like...

1. If e.m.f is NOT a force, but actually energy – and e.m.f is measured in Voltage – then why is p.d. (V) NOT used up? Since we know energy *does* get used up by the component. I know the electrons are just the medium – energy carriers – but Voltage doesn’t mean number of electrons; it means...

I regret to say that I know little of engineering, but, to make a long story short, I'm nagged by two questions about energy conversion efficiency. There is a thread i made titled "giant railguns recycling their own energy in space" in the science fiction & fantasy forum here that explains my...

Homework Statement A proton starts at rest and travels through a potential difference of 8000V. What's it's final speed. Homework Equations ΔEe+ΔEk=0 ΔEk=-ΔEe Ee=qV The Attempt at a Solution I know how to find the correct magnitude, but I am getting the wrong sign. Ek=-ΔEe 1/2mv^2=-qΔV...

Hi All, (First post, be nice). I'm analysing the discharge of a capacitor. Starting from the energy in a capacitor: E = \frac{1}{2} CV^2 This can be represented as follows (seen this elsewhere, there is nothing wrong with this): \Delta E = P \Delta t = \frac{1}{2} C(V^2_s-V^2_f) Where \Delta...

If a fusion reactor could be constructed that runs on Li-7 and hydrogen, and if the energy produced by that reactor where extracted with a direct charging setup, like in a nuclear battery emitting alpha particles, the voltage produced would be the stupendous voltage of 8 mega volts. Now, how do...

Homework Statement One of the three types of radioactive decay is "β decay", during which protons decay into neutrons or viceversa, emitting either electrons (β) or positrons (β+) at high velocity as a result. In one experiment, a β source and β+ source are placed 10 cm apart from each other...

If I were to make millions of contacts or "spots" on a long wire,and connect them in series(or parallel?),then make half of them warmer than the other half,would I get any useful voltage,i.e. electrical energy I could use to power something?

Homework Statement An oil drop is charged negatively. How much charge is on the drop if the Electric Field is 6,400 N/C at a distance of 1.2 m? Homework Equations E=k q/r^2 I don't know if I should be using that equation for this one. The Attempt at a Solution I tried to do E/(k x r^2) = q...

Hello, I have an idea i have been working on for some time. I am a meteorologist and pilot, and i love aviation, especially design. I have been playing with the idea of magnetic lift (as in when one magnet is repelled from another magnet) or electromagnetism in an engine, to create a different...

Homework Statement A charge is to be placed at the empty corner of a rectangle to make the net force at corner A point along the vertical direction. What charge (magnitude and algebraic sign) must be placed at the empty corner if the three charges have the same charge of +8.45 μC?Homework...

I feel like have a chicken and egg type of problem regarding internal resistences because of the following problem: The voltage across a battery with internal resistence is given by the equation EMF-Ir=V Given the voltage across the battery then the voltage in the circuit is V=IR So, if I have...

Found one article saying it is possible to reverse poles of permenant magnet using coiled wire wrapped around magnet, but nothing about the possibility of temporarily reversing or even temporarily weakening the magnetic field.. if there are any magnetism connoisseurs out there..

Homework Statement a. Calculate the energy density of the electric field at a distance r from an electron (presumed to be a particle) at rest. b. Assume now that the electron is not a point but a sphere of radius R over whose surface the electron charge is uniformly distributed. Determine the...

Hi guys I know that in a 6 volt battery 1 columb of charges gain 6 joules of energy do they gain potential or kinetic energy as they move from the negative terminal to the positive terminal ? And how different the energy in Ac electro motive force

Homework Statement Consider point a which is 65 cm noth of a -2.8μC point charge, and point b which is 80 cm west of the charge. Determine (a) Vba=Vb-Va, and (b) Eb-Ea (magnitude and direction)Homework Equations k=9x10-9 V=kQ/r V=kQ(1/rb-1/ra) E=kQ/r2 E=kQ(1/rb2-1/ra2)The Attempt at a Solution...

I've been reading recently about Electric Potential Energy and when introduced with the following situation of two charged plates (one (-) and the other (+)) and a charged particle between them I've been taught the following equation. a) U=E/Q ⇔ E=QU However now when I'm reading about a...

Homework Statement An electron is released from rest from the negative plate of a parallel-plate apparatus, what is the electrons speed one third of the way between the plates. It also asks for the speed at which electron will hit the positive plate if a 450 V potential difference is applied...

Homework Statement A heavy nuclei can be approximately considered as a spherical ball with uniform volume density  = 4/3 * 10^ 25 C/m3. If a nuclei with total charge Q = 92e splits into 2 equal spherical piece and they fly away. What will be the total electric energy change during this...

Could a small amount of water be made somehow to create enough electric current to make a small heater bar hot or to even warm up?

Hi, I'm now in the project research to design a simple low cost and ease installation electric energy detective device. My idea is to put the sensor (etc..) in or within distribution board. Also the device can alarm consumer if they are using more energy. Just want the opinion from you...

Homework Statement So this is from a past test put up as a study guide, but I'm stumped here. The question is: A spark jumps between two electrodes, transferring a charge of 5 μC in 2 × 10−3 s. The constant current I that would transfer the same charge in the same time is The Attempt at...

Hello, I was wondering if someone here could confirm or explain what happens in a resistor. My assumption is that when the electrons enter a resistor, they slow down, thus decreasing the strength of the electromagnetic field and causing the excess energy the field can no longer hold to be...

Hi, I have some questions about these concepts. The equations: Electric field =\frac{K.|Q|}{d^2} Electric potential =\frac{K.|Q|}{d} Electric Force =\frac{K.|Q|.|q|}{d^2} Potential Electric Energy =\frac{K.|Q|.|q|}{d} Electric field and electric force are vectors, electric...

This is probably child's play for most of you, but a guy like me struggles to understand basic concepts. A kick in the pants to set me off in the right direction would be greatly appreciated. Homework Statement How far must the point charges q_1 = 7.60 microCoulombs and q_2 = -24.0...

Homework Statement On planet Tehar, the free-fall acceleration is the same as that on Earth, but there is also a strong downward electric field that is uniform close to the planet's surface. A 2.00 kg ball having a charge of 5.00 µC is thrown upward at a speed of 20.1 m/s. It hits the ground...

Is it Theoretically possible to build a superconducting motor/generator/energy storage device all at superconducting temperatures? The device needs to operate in vacuum, accelerate and decelerate with only field energies exiting the vacuum chamber. I don't have much faith in batteries at 4oK...

Homework Statement part 1. Consider a simple RC circuit consisting of a resistor and a capacitor connected in series to a battery. The resistor has a value of 8kOhms, and the capacitance is 3uF. The final (asymptotic) value of the charge in the capacitor is E*C. At what time is the charge...

HELP!A problem on electric energy storage Homework Statement when two capacitors are connected in parallel and then connected to a battery, the total stored energy is 5.0 times greater than when they are connected in series and then connected to the same battery. What is the ratio of the two...

Homework Statement an electron starting from rest acquires 3.53keV of kinetic energy in moving from A to B. how much kinetic energy would a proton acquire moving from B to A. Homework Equations 1/2mv2 me=9.11e-31 kg mp=1.67e-29 kg 1eV=1.6e-19 J The Attempt at a Solution...

What is the maximum current allowed in a 3.5 W, 220 ohm resistor? The answer needs to be in amps so how would I convert watts to volts?

there is a +q and -q on the x-axis. the +q is L/2 in the negative direction and the -q is L/2 in the positive directions. the distance between the two charges is L. there is a test charge P on the y-axis a distance r from both charges. we had to find the electric energy stored in the dipole...

Hi, I've had this question in my mind for a long time.. When we say that the electrical energy stored in a vacuum is U=1/2\epsilon0*E^2, we assume that the energy is stored in the electric field right? But physically what does that mean? For eg: In a dielectric one can say that the energy...

Homework Statement A 0.50kg ball is suspended in a uniform electric field ( E = 1500 N/C ) as shown in the diagram ... http://img201.imageshack.us/img201/9771/23vl0.th.png Calculate the charge on the ball Homework Equations The Attempt at a Solution I found fg = -4.9 N...

If the electric field is 0, then is the electric potential 0? If the Electric pottential 0 then is the electric field 0? Explain why or why not. .. I rather say my idea on this topic, this my first post I am rather shy...:frown:

Homework Statement Find the electric-field energy density at a point which is a distance of 10.0 cm from an isolated point charge of magnitude 7.30 nC. Homework Equations u = \frac {1} {2} * e_{o} * E^{2} The Attempt at a Solution u = \frac {1} {2} * 8.85*10^{-12} * 7.30^{2}...

Homework Statement Two spheres are mounted on identical horizontal springs and rest on a frcionless table, as in the drawing. When the spheres are uncharged, the spacing between them is 0.0500 m, and the springs are unrestrained. When each sphere has a charge of +1.60 microC, the spacing...

How many joules of electric energy are there in 1 kilowatt-hour?

When electric charges occur in a system, it is possible to determine the electric energy of the system. Which of the following is false: d. The electric energy of the system can only vary when it is converted into thermal energy Why is this answer False? What other factors affect...

Is it possbile to covert heat energy (like that from the surface of a hot radiator) to electric energy? Whats the theory behind this? --thank you.

Electric energy of a dielectric sphere! Hi there, I have attempted a question, I was just seeing if some one can go over it and check if it is ok! Q. The Electric field E inside a dielectric sphere placed between the plates of a large parallel-plate capacitor is uniform. Given that the...