Capacitors Definition and 868 Threads

I was thinking of this following example: Consider you charge a capacitor to its max with a battery, now replace the battery with a light bulb for example. The capacitor is starting to lose all the energy it had stored, is this a result due to entropy? I mean I've learned that an increase...

Homework Statement http://img99.imageshack.us/img99/763/prob45.gif Fig. 1 and 2 show a dielectric slab being inserted between the plates of one of two identical capacitors, capacitor 2. Select the correct answer to each of the statements below (enter I for `increases', D for `decreases', or...

Homework Statement Two capacitors C1=4μf, C2= 12μf are connected in parallel across 12V battery. Then they are collected in parallel, with positive side of one capacitor to the negative side of the other. Find the resulting potential difference. Answer (as on back-pages): 3.50V...

EDIT: That ought to be, "Dielectrics," of course :) Homework Statement An air capacitor is made by using two flat plates, each with area A, separated by a distance d. Then a metal slab having thickness a (less than d) and the same shape and size as the plates is inserted between them...

Homework Statement 1. Is it necessary to discharge the capacitors before starting the experiment in series? Why? 2. Is it necessary to discharge before starting the experiment in parallel? Why? The attempt at a solution For the first one, we connected 3 capacitors in series, and the...

Homework Statement Consider a capacitor that consists of two metal plates of nonzero thickness separated by a positive distance d. When such a capacitor is connected across the terminals of a battery with emf EMF, two things happen simultaneously: Charge flows from one plate to another, and a...

In my lab course, we constructed a circuit that would amplify signals. Here is an image of the circuit. http://desmond.imageshack.us/Himg442/scaled.php?server=442&filename=imgfw.jpg&res=medium My question is, what is the purpose of the capacitors? In other words, if I was making a...

I am a TA for a physics teacher. I wrote a problem that the students did in the lab quiz. The students tried to use conservation of energy instead of conservation of charge, which I used. Both methods seem sound to me, but they produce different answers. I need help figuring out which method is...

Homework Statement 1.When three different capacitors are connected in parallel as in figure 2 in the lab manual: (Choose all relevant answers below) 2.When three different capacitors are connected in series as in figure 1 in the lab manual: (Choose all relevant answers below) a. The...

Homework Statement How many 1.48 µF capacitors must be connected in parallel to store a charge of 1.49 C with a potential of 105 V across the capacitors? Homework Equations Refer to the attempt at a solution. The Attempt at a Solution Also, for the answer exact number, no...

So as I was doing my sample physics midterm, I realized a paradox or a concept that I just haven't fully grasped, hence I see a problem. Homework Statement Suppose we have two parallel plates of a capacitor with: capacitance C, area A, distance of separation D, a constant voltage V=10V...

I have been studying capacitors this week and learned two equations. One is Q=CV and the other is Q=0.5CV. The latter equation is derived from C-V graph. From this it shows that half the charge delivered is stored. I am very curious to know where the other half of the charge go and why is the...

Homework Statement Three capacitors, of capacitances C , 2C and 3C respectively are connected in this order in series to a voltage U battery. After they are charged, the middle capacitor (2C) is disconnected and then connected back again with reversed polarity. Find the charges on each of the...

There are two types of capacitor, non-polarized and polarized. The non-polarized capacitor holds equal amounts of charge in each of its two plates so that a difference in charge is only achieved when electrical current from a power supply transfers electrons from one plate to another to cause a...

Homework Statement A circuit is constructed with five capacitors and a battery as shown. The values for the capacitors are: C1 = C5 = 4.6 μF, C2 = 1.7 μF, C3 = 5.7 μF, and C4 = 2.7 μF. The battery voltage is V = 12 V. 3) What is Q5, the charge on capacitor C5?Homework Equations Parallel...

Suppose we have two metal plates, one with a charge density of 3 C/m^2, the other -3C/m^2 We are told that the charge density on surfaces 1 and 4 are zero and the charge density on surface 2 is 3C/m^2, on surface 3 is -3C/m^2 Any reason for that? Is it possible that the charge density on...

Homework Statement Two parallel plates, each having area A = 3118cm2 are connected to the terminals of a battery of voltage Vb = 6 V as shown. The plates are separated by a distance d = 0.35cm. You may assume (contrary to the drawing) that the separation between the plates is small compared...

Homework Statement What is Q5, the charge on C5? V of battery = 12 V. Homework Equations C=Q/V The Attempt at a Solution V1 + V5 + V(2,3) = Vb V1 + V5 + V4 = Vb I have three unknowns and 2 equations. :(

I have (conceptual) questions about this question posted before: https://www.physicsforums.com/showthread.php?t=386071 On the second part of the question (part B: The switch is opened at t = 0s. At what time has the charge on the capacitor decreased to 12% of its initial value?), why does...

Homework Statement A 24 V battery is used to charge two identical capacitors CL = CR = 6 µF, in parallel so Q(CL) = Q(CR) = 0.000144 C the battery is removed, and the energy stored in the system is .003456 J Next a dielectric with k = 1.4 is inserted between the plates of CR, fully...

Homework Statement Two capacitors having values of 10 μF each are connected in parallel and then hooked up to a 9.0 V battery. How much energy must the battery supply to charge the capacitors? *a. 8.1 x 10-4 J b. 9.0 x 10-5 J c. 1.6 x 10-3 J d. 2.0 x 10-4 J e. 2.3 x 10-5 J...

Homework Statement http://session.masteringphysics.com/problemAsset/1006859/35/37016.jpg Heres what I did Vtotal=V1+V2/2+V3/3 Vtotal=v1+5/6 V2,3 Vtotal -5/6 V2,3 = 1/6 V1 This is wrong, I want to know my mistake, please help. Thank you

Homework Statement Two capacitors C1 & C2 are independently charged to potentials V1 & V2. Then the two capacitors are connected to each other, where each positive plate is connected to the other's negative plate. What is the final charge on capacitor 1 in terms of C1, C2, V1, V2? Homework...

Homework Statement An infinitely long solid conducting cylindrical shell of radius a = 3.1 cm and negligible thickness is positioned with its symmetry axis along the z-axis as shown. The shell is charged, having a linear charge density λinner = -0.49 μC/m. Concentric with the shell is another...

Homework Statement The 2290.-nF capacitor is then disconnected from the 19.2-V battery and used to charge three uncharged capacitors, a 175.-nF capacitor, a 280.-nF capacitor, and a 375.-nF capacitor, connected in series. After charging, what is the potential difference across each of the...

Two Capacitors are connected in series (3 microfarad and 6 microfarad) with Vab=10V. Battery is disconnected and the loose ends of wire are connected. What happens to the potential difference?Would it be zero..charge? I can't figure it out...sounds like a short circuit?

Homework Statement In the arrangement shown in the figure below, a potential difference DeltaV is applied, and C1 is adjusted so that the voltmeter between points b and d reads zero. http://capa.physics.mcmaster.ca/figures/sb/Graph26/sb-pic2667.png This "balance" occurs when C1 = 3.56 µF. If...

Homework Statement When the voltage across the two plates of a capacitor is increased then: *a. the charge will increase b. the charge will decrease c. the capacitance will increase d. the capacitance will decrease Homework Equations CV=Q The Attempt at a Solution...

Homework Statement A capacitor has been charged by connecting it to a 24 V battery. How much work was done in charging this capacitor, when at the end of charging, its charge is 3 µC? a. 8 µJ b. 12 µJ c. 36 µJ *d. 74 µJ Homework Equations W=E=Q2/2C=QV/2 The Attempt at a...

Trying to learn the basics of capacitors, but I'm hung up on a conceptual issue. It seems that capacitors must be charged up, generally with the help of a current from outside the capacitor, such as a flow of electrons that pile up on one of the plates. So in that sense, the capacitor must be...

In the circuit, all elements are ideal. For time t<0, S1 remained closed and S2 open. At t=0, S1 is opened and S2 is closed. If the voltage Vc2 across the capacitor C2 at t=0 is zero, the voltage across the capacitor combination at t=0+ ?? I tried this problem. Obviously, Vc1(0) = 3V ...

hello i need help with this, what is the differential equation for the voltage v2 (t). http://www.imageurlhost.com/images/mc2qqp4kax37kvm51h1h_circuit.jpg sorry for my english

It is neither a homework nor coursework problem, but I really want to know the solution. Homework Statement 3 charged capacitors are connected as shown in the diagram. What will be their final charges, potential difference when equilibrium is reached? Units are arbitrary...

i'm given a circuit that contains a 15 volt battery and a resistor that has a power rating of 1/4 watt and a resistance that must be greater than 1 kohm. I'm told that no matter how i set it up, i cannot exceed the 1/4 watt power rating of the resistor. this makes sense. i work out the max power...

Homework Statement Find the h parameters of the following systems:- ---L---------C-- : : R : : ---------------- L= j5 ohm C=-j5 ohm R=1 ohm Homework Equations The above questions has to be solved manually as well as simulated...

Homework Statement Capacitors C_1=6μF and C_2=2μF are first charged by connecting them in parallel across a 250V battery. The capacitors are then disconnected from the battery and connected positive plate to negative plate and negative plate to positive plate. Calculate their charges...

Can anybody tell me which are the formulas to find energy in capacitors in series and in parallel?

Hey, I just stumbled apon this question in a past paper that I am having trouble understanding, http://img190.imageshack.us/img190/6266/78199113.jpg For a) its just straight forward isn't it, C = Aε/d even though they are moving. b and c I am having trouble imagining the...

Homework Statement Homework Equations Q = CV The Attempt at a Solution It's already solved for me; I just don't understand it. In figure (b) it looks like there are two separate conductors: one on top, and one on the bottom. The top piece has +Q on the left side and -Q on the...

Capacitors -- what does same potential mean? Homework Statement Revered members, When the capacitor is fully discharged, the plates of capacitor are at same potential. I want to know the interpretation of the term same potential. Homework Equations The Attempt at a Solution...

A 25 uF and a 40 uF capacitor are charged by being connected across separate 50 V batteries. The capacitors are then disconnected from their batteries and connected to each other, with each negative plate connected to the other positive plate. What is the final charge on each capacitor, and what...

1. An experiment is run to determine the validity of numerous electrostatic principles. A small ball of mass 6.50 x 10-3 kg with a charge of ±1.50 μC is suspended from a non-conductive wire and hangs between two parallel plate capacitors. An angle of 30.0° is measured between the wire and the...

Homework Statement Four parallel metal plates P1, P2, P3, and P4, each of area 7.50 cm2, are separated successively by a distance d = 1.06 mm, as shown in the figure below. P1 is connected to the negative terminal of a battery, and P2 to the positive terminal. The battery maintains a potential...

Homework Statement Three resistors, three capacitors, a battery and two switches are connected in the circuit shown below. The values of all circuit elements are given in the figure. Originally, the switches S1 and S2 are open (as shown) and all of the capacitors are uncharged. At time t =...

Homework Statement Three capacitors C1–C3, all initially uncharged, are placed in the circuit show above. The capacitances are C1=15.2 μF, C2=9.8 μF, C3=4.4 μF, and the battery voltages are V1=20 V, V2=20 V, V3=5 V. What is the magnitude q1 of the charge on capacitor C1 once equilibrium...

Homework Statement A capacitor is completely charged with 670 nC by a voltage source that had 200 V. What is its capacitance?==== 3.35×10-9 F 9(I got this y doing Q/V) The initial air gap of the capacitor above was 7 mm. What is the stored energy if the air gap is now 10 mm? Now...

1. Problem Statement Some capacitors are marked 48uF, safe working voltage 25V. Show how a number of these capacitors may be connected to provide a capacitor of capacitance: a) 48uF, safe wroking voltage 50V b) 72uF, safe working voltage 25V Homework Equations obviously C total in...

I'm a little confused about this problem. I attached the pic. The solution manual states " capacitors C1 and C3 are in series with each other and in parallel with capacitor C2." I don't understand why it has to be C1 and C3 in series which is parallel with C2. Can't it also be C2&C3 in...

Good day All: How can I prove that a linear relationship exist between the displacement (d) and the capacitance(C) of a Variable dielectric capacitor? I know that the equation for a capacitor's capacitance is: C= εA/d

Homework Statement Quick question. If you were to find the Thevenin's equivalent circuit between the terminals of an inductor, and thus calculated the time constant using Rth, would the time constant be same as if you were to not? Same question for capacitor circuits