Capacitor Definition and 1000 Threads

Hello everyone, I was wondering how one would calculate the three-dimensional charge density (per volume) in a capacitor plate with a given thickness. I know how to calculate the charge density on the surface based on the capacitance and voltage, but how would one calculate the comprehensive...

[SIZE="4"]Definition/Summary A capacitor (or condenser) is something across which charge cannot move, but across which an accumulation of charge on one side can affect charge on the opposite side. So a capacitor does not conduct direct (DC) current, but does conduct alternating (AC)...

The capacitor and dielectric Homework Statement A small dielectric plate is pushed between parallel plates of an (1) isolated capacitor to the half of its length. If the dielectric is let to move freely, what's going to happen to it? (2) What would happen with the dielectric if the capacitor...

What would have been if the opposite and equal charge wouldn't have been induce on 2nd conductor in parallel plate capacitor when connected to a battery

Hey guys! New to physicsforums. I wanted to ask a more conceptual question regarding RC time Circuits. I spent some time trying to derive the equations, and I feel like I'm not setting up the problem correctly. Here's my attempt: Solutions according to profecssor: 1)...

Why do the capacitance increase with increase in dielectric constant(K) of the medium between the capacitor?

We know that the main use of capacitor is to store charge in the form of electric field,and we want it to store as much charge as possible without leaking and we try to decrease the potential difference between the conductors.But if we increase the charge of the conductor it will consequently...

Consider a parallel plate capacitor, with distance between plates = d_1 . As we know the voltage between them V = Ed . The electric field of two parallel plates is perpendicular to the surface and of the same intensity no matter where we are between the surfaces (accurate for small d's). Now...

I want to know the meaning of energy dissipation...is eergy dissipation and energy consumption are same things?? inductor and capacitor store energy which can be used later... what is then energy dissipated?? is it the heat loss in these elements?? I mean..heat loss is what we say energy...

Finding the charge on each capacitor in series Homework Statement In the circuit in the figure below, assume the resistance values are R1=1,400Ω and R2=2,500Ω, C1=55μF and C2=15μF, and the emf=5.5 V. The switch is labeled S. Consider the circuit in the figure below and assume the switch...

As I understand it if you charge two plates as in a capacitor and then disconnect the voltage source and pull the plates apart to an arbitrary distance the voltage at the terminal increases. Is that correct? Will that voltage continue to increase? Is there a point that the voltage will stop...

dear sir the charge on clouds and ground can be different and this causes lightning due rain only. i want to know more about the process that causes it

http://imgur.com/WPZWkJf The final voltage across the capacitor is the same as the source voltage is 90 V since a capacitor behaves as an open circuit in presence of a DC voltage. But what about the resistor? He is placed in series with the capacitor and wouldn't it be: final voltage...

i'm building fm radio jammer for project for my ee class in physics department. a circuit is here. http://www.circuitstoday.com/fm-radio-jammer i bought the components, soldered on PCB. it hasn't worked. an oscilloscope shows sine oscillation even if there is no L and C for tank circuit...

Homework Statement This is not a true homework problem but rather my interpretation of RC Capacitor theory. What is the action of a capacitor in RC first-order circuits?Homework Equations The Attempt at a Solution From what i understand, when a capacitor is being charged, charges move from...

Hello all, I was reading this post on calculating the capacitor charge time: https://www.physicsforums.com/showthread.php?t=145203. My problem is i have a capacitor (1000uF) and i want to determine its charge time but don't know the R value, is it something i chose arbitrarily or should it...

Homework Statement I was told that I can measure the "resistance" of a capacitor using 3 methods: 1. "The direct method" R = \int_1^2 \frac{\rho}{A} ds 2. "Ohm's Law" R=\frac{U}{I} U=\int_1^2 E ds E=\rho J = \frac{\rho i}{A} 3. "The analogy between electrostatics and electrokinetics"...

Homework Statement In the circuit below, the capacitors labeled C1 and C2 both have capacitance C. They are connected through a switch and a resistor of resistance R. Capacitor C1 is initially charged with a potential V1(0) at time t = 0, while capacitor C2 is uncharged at time t=0. At...

need advice please... what happened when I insert additional mesh between plates inside capacitor's dielectric ? first I charge between plate 1 (-) and the mesh (+). I know this no problem from this link http://personal.ee.surrey.ac.uk/Personal/D.Jefferies/perfcap.html after fully charged, I...

Homework Statement If you increase the charge on a parallel plate capacitor from 3μC to 9μC and increase the plate separation from 1mm to 3mm, the energy stored in the capacitor changes by a factor of... Homework Equations U = 1/2QV or 1/2CV^2 The Attempt at a Solution I'm not sure which...

Please have a look at the following links: http://www.eaton.com/ecm/groups/public/@pub/@electrical/documents/content/sa02607001e.pdf (Table 3) http://www.electrical-installation.org/enwiki/Power_factor_correction_of_induction_motors FigL24) - For power factor correction, why would the...

Would it be wrong to describe Capacitance as being the charge stored per unit volt? I have found on the internet that the definition of a Farad is the charge needed to cause one unit volt. Which means that the definition of Capacitance should surely be the same because the internet definition...

Hi.. I am working as a signalling engineer in Railways. This weekend i am going to give a presentation on super capacitors and their use in railway systems. Most importantly i am going to show how we can replace batteries with super capacitors (EDLC). The problem i am facing is i don't have any...

Hi, I just registered and don't know if I opened the post in right place, this is not a homework question, only something I wonder. I know that electric field energy density in a parallel-plate capacitor is; u= ε * (E^2) / 2 and I know how this formula derivated for parallel-plate...

Homework Statement A dielectric-filled parallel-plate capacitor has plate area A = 15.0cm2 , plate separation d = 5.00mm and dielectric constant k = 3.00. The capacitor is connected to a battery that creates a constant voltage V = 5.00V . Throughout the problem, use ϵ0 = 8.85×10−12C2/N⋅m2 ...

Homework Statement Two parallel plates, each having area A = 3558 cm2 are connected to the terminals of a battery of voltage Vb = 6 V as shown. The plates are separated by a distance d = 0.54 cm. 1) What is Q the charge on the top plate? 3.5*10^-9 C 2) What is U, the energy stored in...

I have attached one circuit. I don't know why we consider the rightmost capacitor gets short circuited. And what do you mean by short circuit ?

http://photouploads.com/images/photo1igi.jpg These formulas have been provided to me for use in RC circuits. However, they haven't been defined in the lecture notes. I know Vc = voltage across the capacitor, but isn't that what Vc(t) is as well? Is there any difference between the two? Thanks

Hi Ive got some calculations to do on amount of charge on a capacitor with respect to t. Formula for amount of charge on a capacitor is Q=5.7ln4.5t I need to determine the rate of discharge with different values of t, t=5ms t=7.5ms I know i need to differentiate the formula...

Homework Statement I need to rearrange the equation for exponential growth of voltage across capacitor during charging. Homework Equations Equation is Vc=Vs(1-e^-t/CR) I need to find out how long it takes for Vc=26v with Vs=40v thus rearranging the equation making t the subject...

Homework Statement In the following RC circuit, the capacitor is in the steady state. The initial separation of the capacitor plates is x0. If at t = 0, the separation between the plates starts changing so that a constant current flows through R. Find the velocity of the moving plates as a...

Homework Statement a resistor of 1000 ohm is connected in series to a capacitor and ac supply of frquency 50hz, if the phase diffennce of voltage supplied and current of circuirt is 30 degree, what's the capacitance of capacitor? the V max and I max in not given , how to do this ? help...

Homework Statement Two capacitors ##C_1## and ##C_2## (where ##C_1 > C_2##) are charged to the same initial potential difference ##V_i##
, but with opposite polarity. The charged capacitors are removed from the battery, and their plates are connected as shown in Figure a. The switches...

Physics homework problem -- design a capacitor Homework Statement An engineer needs to design a capacitor with a capacitance of 1*10-6F using a material with a dielectric constant 260. If the dielectric strength of the material is 8*106 N/C, and the maximum voltage that the capacitor is...

Homework Statement Homework Equations C =Q/V c = capacitence q = charge v = potential difference U = Q2 / 2C U = potential energy The Attempt at a Solution I'm just stuck on b. I tried doing Qeq= √(2UC) then using the fact that q1+q2 = Q which is Qeq since charge should...

I am not able to solve this problem I am thinking that Co would be charging in reverse polarity switch is shifted to 2 position, so change in energy of capacitor will be released as heat energy, i.e twice the energy of stored capacitor.

I am trying to calculate the maximum current drawn from a capacitor that is connected to a resistor of a very low value (a few mΩ). Because the resistor does not have a large resistance as I've seen with many V/t and I/t graphs for capacitors connected to resistors, where the decay of the curve...

Does anyone have any idea how I could begin to examine the field of two conducting plates which are side by side instead of parallel ?

Homework Statement A parallel plate capacitor having plate area equal to A and the separation between the plates equal to d, is placed in a stream of conducting liquid with resistivity r. The liquid moves with constant velocity v parallel to the plates of capacitor. The complete system is...

Suppose we have an un-charged parallel plate capacitor separated by some distance (say d). As the capacitor is not charged, the plates are in neutral position. Means, it has equal no. of electrons and protons. So, Potential difference across the plates is 0 because energy possessed by 1 C of...

Homework Statement here's my question and the working in the same photo.. my question is to find to find the effective capacitance in the circuit i use (1/c1 +1/c2)^-1 , why should can't just take effective c = (1/c1 +1/c2)^-1 but must times 2 ? since (1/c1 +1/c2)^-1 is already effective...

For some reason I had to apply a capacitor in parallel to an AC circuit which has reduced the power factor as a result some power generating AC equipments are complaining (overload). Now I need to apply an inductor in parallel to fix that. For that I need a formula which gives me the...

In connecting a battery to a capactor, doubling the spacing halve the capacitance while keeping voltage fixed. Why?

Homework Statement A resistor, inductor, capacitor are connected in series to an AC source. The AC source is operating at the resonance freq. Which are true? 1.The current is in phase with the driving voltage. 2.The peak voltage across the capacitor is greater than the peak...

Hello PF, Homework Statement The capacitor C_1 is connected to a battery as shown. After being charged, it is connected to the capacitor C_2 and the second battery as shown. When all the charges come to rest, what will be the charge on capacitor C_2? http://imgur.com/4ciJRrn Homework...

Homework Statement This is just an example from the book. See images. I am not sure how they found v(cap) to be equal to 97.3 V. Homework Equations Nodal Analysis The Attempt at a Solution 3 A - i(ind)/48 - i(res)/100 = v(cap) Too many unknowns, that's why I think I'm way...

A capacitor in an AC circuit. What is the amplitude of the current?? Homework Statement I really do not know how to approach this problem. What confuses me is that when calculating the % error I'm suppose to have a theoretical or accepted value and a measured value. So how do I determine...

Homework Statement A parallel-plate capacitor with plates of area (0.5m) * (1m) has a distance separation of 2 [cm] and a voltage difference of V = 200 [V], as shown in Fig. a) Find the energy stored b) keep d1 = 2 [cm] and the voltage difference V, while increasing d2 = 2.2...

Homework Statement http://postimg.org/image/4m0huqxpj/ Homework Equations v(t)=v(infinity)+ [v(0) - v(infinity)]^e(-t/RC) The Attempt at a SolutionI found Vo(0) to be 8V, but I'm not sure about about v(infinity) and R If the switch is at B and the capacitor is an open circuit at steady...

Capacitor problem -- Calculate the heat in connecting wires Homework Statement A 5.0\muF capacitor is charged to 12 V . The positive plate of this capacitor is now connected to the negative terminal of a 12 V battery and vice versa. Calculate the heat developed in the connecting wires...