Capacitor Definition and 1000 Threads

1. Homework Statement The problem is above, I am having a hard time figuring out why the right answer for part F is "greater than." Homework Equations Ucapacitor = 0.5 * C * V^2 The Attempt at a Solution [/B] My problem is figuring out the logic in how the capacitor's energy would...

I'm a high school junior and doing a project on ben franklin. specifically I'm making a model of his electric motor which used two Leyden jars to operate. I want to make it a working model but I cannot get the leyden jars work. can anyone explain to me how to construct a historically accurate...

1. Homework Statement A fixed parallel plate capacitor is charged. A point charge is starting to move with an initial speed 1.0 m/s at shown initial position. The capacitance is 5.0 F. The mass of the point charge is 0.80 kg. Assume that the plate length is infinite. No gravity. The initial...

Homework Statement We just started capacitors in class and we were introduced to the formulae q=CV and i = C*dV/dt In the notes it said that if the voltage across a capacitor were to change instantenously, the capacitor current would be infinite. It goes on to say why this is never possible...

In a RC circuit is voltage through a capacitor always consider negative no matter if you're going with or against the current when setting up a voltage equation?

Homework Statement Calculate the equivalent capacity of the capacitor system between points ##x## and ##y## Homework Equations ##C=q/V## The Attempt at a Solution I'm asking about this problem because I know how to calculate ##V_x-V_y##, but I don't know how can I extract the equivalent...

Homework Statement In the following diagram, The voltmeter reading is 5 volts when the switch K is open and C1 is not charged. When you close K calculate the following: 1- Voltmeter reading 2- Charge of each capacitor 3- Voltage of each capacitor Homework Equations Usual electronics equation...

Homework Statement Homework Equations C = q / voltage The Attempt at a Solution OK. [/B] By Kirchoff's Voltage Law, we have: EMF - ( q / Capacitance)x - (q/Capacitance)y = 0 Now. I know that having the dielectric increases the capacitance of X, so the voltage drop across it is smaller...

Hi, I am trying to build a solar powered toy car. And no its not for my son, its for my own curiosity. The problem I am having is that...while the solar panel is sufficient to rapidly turn the (4) micromotors 6 inches away from a lightbulb it isn't sufficient to even turn the wheels when I put...

Good Evening/Morning/Afternoon Everyone, Question: Why is it that demonstrations of Van de Graff generators use Leyden Jars in series to get bigger sparks? If a spark gap's size determined by voltage, and Leyden jars are simply to be treated as capacitors which wouldn't increase voltage, why...

Homework Statement [/B] Two long, coaxial metal cylinders are separated by a material of conductivity sigma and dielectric constant epsilon. The radius of the inner cylinder is a, the radius of outer cylinder is b, and the length of both is L. Suppose that the inner conductor is held at a...

Homework Statement find Vc(0) Homework Equations Node analysis , ohms law The Attempt at a Solution Hi, I'm trying to find Vc(0). I used node analysis but I'm stuck in eq 1. I'll appreciate if someone can give me some suggestions. Thanks

Homework Statement Prove that the total energy initially stored in the electric field inside the capacitor is equal to the total electrical energy eventually dissipated by the bulb. A 5 V DC power source charged the capacitor. The capacitor was then connected in series with a light bulb with a...

I noticed that I could get a minor belt off my 3 x 1.5KW compressor. I attached my meter to a mains supply 'socket earth', and to 'the chassis'. I watched the AC voltage gradually rise... perhaps increasing in speed slightly as the potential difference increased between the chassis and earth...

Homework Statement http://imgur.com/a/4YfkJ http://imgur.com/a/4YfkJ Homework Equations for t<0 I understand that Capacitor acts as an open circuit and goes away but why did the 90v and 6ohm resistor disappeared? is it because current doesn't go that way? and also in that KCL at node V1...

Homework Statement Homework Equations .Q = CVab The Attempt at a Solution I am having a hard time understanding when to put the capacitance in the denominator. I get that Voltage = Charge/Capacitance, but for the equation circled in red "q1/c + q2/c = q3c" ... I don't get why each of...

Homework Statement Assume you have C1, C2, C3 capacitors and each one of them have a specific charge. Now imagine you connect them to one circuit (Just as in the picture below). Determine the charge on each capacitor after the movement of charges stop Homework Equations Kirchhoff's law The...

hi, i have a question which i was hoping someone could help with,a series circuit featuring a capacitor (C) charging via a 1Mohm (R) resistor and a 12volt dc supply(VS).i know the equation to describe VC is VC=VS(1-e -t/RC)the question is: assuming VC is 2V after a time of 4 seconds, determine...

Homework Statement A potential difference Vab = 46.0 V is applied across the capacitor network of the following figure. If C1=C2=4.00μF and C4=8.00μF, what must the capacitance C3 be if the network is to store 2.80×10−3 J of electrical energy? Homework Equations U=(1/2)CV^2 (1/C) = (1/c1) +...

Hey SIr , (Addressed to Sir J D Grififfiths) Last year when I took basic electricity and magnetism course , my instructor discussed some interesting ideas which you discussed in your book ''Introduction to Electrodynamics'' ,one of that was calculating force exerted on a dielectric while it's...

Hi. If a plate capacitor is charged with some charge ##Q##, then there's a voltage ##U=Q/C## between the plates. The electric field between the plates is ##E=U/d##. Voltage is path independent, if I connect the plates with a cable of length ##l\gg d## the voltage across the cable is the same...

Homework Statement In the circuit shown in the figure, C1 = 1.0 µF, C2 = 1.9 µF, C3 = 2.8 µF, and a voltage Vab = 30 V is applied across points a and b. After C1 is fully charged the switch is thrown to the right. What is the final charge and potential difference on each capacitor? Homework...

Hello, I have been searching for a mathematical analysis regarding the edge effect of a parallel plate capacitor. Could anyone help?

Hi, A time-varying (sinusoidal) voltage source is applied to a parallel plate capacitor of length d. Then the E field will vary according to E(t) = V(t)/d. However, this suggests that, for any given time, the E field is constant with respect to spatial coordinates. Therefore, the curl of E is...

Hi. The capacitance of an ideal plate capacitor (coaxial cable) goes to zero as the plate distance (outer radius) goes to infinity. This doesn't happen with concentric spheres as we let the outer radius go to infinity, hence a single sphere has a nonzero capacitance. What's the exact reason...

Hello! I am bit confused about kirchhoffs law with capacitors. So if I have a battery and resistance, I obtain V-RI=0. But from what I read, if I have a capacitor and resistance (so discharging capacitor), the equation reads R(dq/dt) + q/c = 0, which is equivalent to RI + q/c =0. Why in this...

I need a voltage divider to make it possible to measure voltage on the 3S LiPo battery that delivers around 11 V using a device that measures up to 4 V (approx). I can make one, no problem, just solder two resistors with resistances in the more or less 1:3 ratio (measured output is sent as a...

Hello. I'm now taking accelerator physics class and the lectures said in the thermionic electron gun, anode metal mesh should be grounded in order to prevent electrons which traveled beyond the mesh from coming back due to the electric field lines. Without grounding of the anode, I believe...

Homework Statement Homework EquationsHEAT PRODUCED=WORK DONE BY BATTERIES - ENERGY ABSORBED BY CAPACITORS The Attempt at a Solution INITIALLY BEFORE SWITCH CLOSED :Initially a current flows only in the left most loop involving 4 microfarad capacitor.The charged on the capacitor during...

Hi. Assume we connect both plates of a capacitor to ground and disconnect again, leaving them at ground potential. Then we bring electrons from one plate to the other, until there is a voltage difference ##\Delta U## between the plates. Compared to ground, one plate has the potential...

I am planning to conduct an academic experiment involving an electromagnetic projectile. I originally planned to build a rail gun powered by a 400V 2200µF capacitor, I've read a lot of discussions that say rail guns require a tremendous amount of current. Is this capacitor sufficient to propel...

When the inner sphere of a spherical capacitor is grounded and a charge is given to the outer sphere, then it is said that two capacitors are in parallel : 1) outer sphere and the ground and 2) inner sphere and the inner surface of the outer sphere. My question is about the second one. Since...

Suppose we have equal and opposite charge densities on a parallel plate capacitor. Let the plates be separated some small distance d (small when compared with the plate size). Now slowly separate the plates so that their separation is now doubled to 2d. We have done work and the electrostatic...

Homework Statement I am trying to find the capacitor voltage in the following picture: Find i(t) in the figure below. Assume dc steady state conditions are valid for t<=0. Homework Equations i=c(dv/dt) KCL The Attempt at a Solution At t<0 I found Vc to be 8 volts which should be correct...

I've been looking through the internet and so fair I haven't found anything too clear on this. Some articles have said that plasma can be affected by magnetism and can be conductive, but my question is, will it become positively/negatively charged while current is flowing through it, and if it...

I have a problem that I have encountered during research. The setup for this scenario is that I am placing two contacts on top of a piece of diamond. What I need to be able to do is calculate the Electric Field at a point within the diamond when I apply a voltage to the contact. The point of...

Homework Statement A bypass capacitor increases gain in the mid-band region. Explain how with the figure and small signal model. Assume gm=0.5mS. Homework Equations Rs = 1 k Ohm The Attempt at a Solution With the bypass capacitor, the source would be treated as grounded and the equations...

Picture a charging capactor, you know the E field, and the induced B field, the energy flow is just EXB. Please describe for me in rough terms the energy flow vector field near and far from the slowly charging capacitor? The flow of energy must ultimately come from the source of energy that...

I was looking up capacitors and the E-field that is produced by a capacitor and I couldn't find much literature about how the E-field changes when AC is flowing through a capacitor. Is this similar to the propagation of an antenna? Do capacitors radiate? Could a capacitor be considered a dipole...

Homework Statement An electron is launched at a 45∘ angle and a speed of Vo = 5.0×10^6 m/s from the positive plate of the parallel-plate capacitor towards the negative plate. The electron lands 4.0 cm away. Homework Equations F = ma = qE v = d/t s = vt -(1/2)at^2 x = 0.04 m The Attempt...

Homework Statement A voltage is applied across the capacitor network in the image shown Below (if it loaded I can only see a small panel with IMG on it), which of these individual capacitors has the highest voltage across it Homework Equations...

Dear Forum Members, I am looking for someone who can help me to model the behavior of a photodiode in parallel with a capacitor. I want to model the behavior of a device that I have developed. As you can see in my attached file, the photodiode shows a current-to voltage characteristic with a...

From the view point of quantum field theory how does one describe the electromagnetic energy density between the plates of a charged capacitor? Thanks!

Homework Statement Two capacitors of capacitances 3μf and 6μf are charged to potentials of 2V and 5V respectively. These 2 charged capacitors are now connected in series.Find the charge and potential difference across each of the capacitors now. Homework EquationsThe Attempt at a Solution...

<< Mentor Note -- Thread moved from the technical forums,. so no HH Template is shown >>[/color] Hello! I have a question on Electromagnetics. Could anyone check if I am on the right track? Here is the proposed problem: Consider a spherically symmetric current distribution, which is radial and...

Homework Statement I'm trying to calculate the voltage drop across a 60uF and a 30uF capacitor in series, powered by 60V. Is the formula for voltage drop across capacitor opposite of the formula for resistor, where resistor is R1=R1/(R1+R2) while capacitor is C1=C2/(C1+C2)? Homework...

What will happen to the force between the capacitor plates (Will increase or decrease or remain constant) if we introduce a dielectric between them? As per the answer given the physics textbook , the force will remain same? But as per my understanding the force should decrease since electrical...

Hi everyone, 1. Homework Statement It takes 18 J of energy to move a 0.30-mC charge from one plate of a capacitor to the other. How much charge is on each plate? Homework Equations -We/q = ΔV C = Q/V The Attempt at a Solution -18J/0.3.10-3 C * 15.10-6 F = Q Q = -0.9 C The problem is...

This has been confusing me a lot lately. I built a type of battery derived from a solar cell that outputs a constant voltage of 0.5 Volts. My original plan was to work out a method to boost this voltage to around 1V to power a joule thief and light an LED using a capacitor charged by the cell...

Homework Statement A capacitor, is fully charged by a battery. The battery is disconnected and a dielectric is inserted into the capacitor. Which of the following is true? I. Voltage will stay the same II. Potential energy of the capacitor will increase III. capacitance will increase...