Capacitors Definition and 868 Threads

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...

Homework Statement Two capacitors C1 and C2 and a resistor R are all connected in series. At t=0, a charge Q1 resides on C1 and a charge Q2 on C2 (Q1 > Q2; C1 < C2), and the positive plate on C2 is connected to the negative plate on C1. a) In a first experiment, the positive plate on C2 is...

Capacitors 1, 2 and 3, have capacitances equal to 2.00 μF, 4.00 μF, and 6.00 μF, respectively. The capacitors are connected in parallel, and the parallel combination is connected across the terminals of a 200-V source. The capacitors are then disconnected from both the voltage source and...

Looking at the units involved with the Ohm's equation and the capacitance equation I found this much: V=iR C=q/V So... C=q/(iR) and i=q/t so... C=t/R and R/t=1/C Basic stuff. So capacitance is proportional to the inverse of the resistance. This would help explain why resistors...

Homework Statement Calculate the charge on and the potential difference across each capacitor Homework Equations C|| = C1+C2+C3... C(Series) [(1/C1)+(1/C2)+(1/C3)+...]^{-1} Q=CV V=Q/C The Attempt at a Solution I already know that C_{123} = 16/9 \muF I also already know that...

How to build a DC-->AC converter using resistors capacitors and diodes (no inductors) I have been trying to learn electronics (I am familiar with the principles, just have no experience designing complex circuits to fulfill purposes), so I went to RadioShack, got myself: breadboard assorted...

I know that in order to charge a capacitor, you must have a power source voltage greater than or equal to the desired voltage in the capacitor. Knowing this, is there any way to achieve a higher voltage DC(from a lower voltage DC) without using a step-up transformer?

I was wondering... exactly how do capacitors charge in a series? Let me clarify what I mean. Let's say that I have 5 capacitors in a series. How do the ones in the middle gain a charge if they are not connected to the actual power source? I know that this is probably a stupid question, but...

Homework Statement Two capacitors, C1 = 20 micro Farads and C2 = 5 Micro Farads are connected in parallel and the resulting combination is connected to a 12-V battery. Find (a) the Equivalent capacitance of the combination, (b) the electric charge on each capacitor, (c) the potential...

What is the conceptual perspective of why equivalent capacitance is in parallel is more than the individual capacitance? (assume we have a parallel network of capacitors of equal value) I know the formulae, decoded the concept behind the eq cap in series but couldn't make any sense out of the...

Homework Statement All capacitors of the open circuit shown below are discharged when, at time t=0, the switch S1 is closed. At some point later, at time t = t1, the switch S2 is also closed. What is the charge Q2(t2) on the capacitor C2 at time t = t2 > t1...

Hi there, okay my Question is on discharging capacitors. the equation for instantanious voltage of a capacitor whilst dischargeing is : v=Vi*e^-t/R*C However I am not sure how to find the time for a capacitor to completely discharge to zero volts. When I transpose for t...

I am trying to solve the problem another poster asked about in https://www.physicsforums.com/showthread.php?t=382491. I realize how the problem is supposed to be solved, and that you have to start with the rightmost 3 capacitors because none of the other capacitors are in series or in...

Homework Statement I have managed to calculate the first part of the question but the second part b I keep getting wrong. I was wondering whether you might give me some guidance. I am trying to find the current after 50s in part b below. Homework Equations time constant = RC The...

For a given capacitor that is connected to a battery, the amount of charge acquired by each plate is proportional to the magnitude of the potential difference V between them. Q = CV Is it correct to say that the voltage (potential difference V) applied across the capacitor plates is what...

Why do capacitors charge exponentially? and do not explain by equations.

Two capacitors are connected in parallel to each other and a battery. There are two switches, S1 between the first capacitor and the battery and S2 between the two capacitors. At first, S2 is open and S1 closed, so the first capacitor charges, then S1 is opened and S2 closed, so the charge is...

I am a mechanical engineer and not an electrical engineer, so feel free to snicker at my question. Can a capacitor have more than two plates? If so, what happens? Is it less efficient? How would a tripple- or quaduple-plate capacitor behave differently than a dual-plate capacitor, assuming...

You have a circular capacitor (radius = R). Find the magnetic field from the central axis, for r > R? I have solved the first one for r<R by using ampere's law: /B dr = my(I + d/dt(flux of electric field)) the answer is hard to write in a post like this, but I will do if necessary...

Homework Statement A capacitor is charged through two bulbs (Figure 2a) and then discharged through a single bulb (Figure 2b) a. Show the appropriate rays on the bulbs in each circuit b. Mark each of the following statements as True or False. If the statement is false edit/alter the statement...

I heard a point made that capacitors can still retain a dangerous amount of charge in an electronic circuit (inside your computer, say) even when everything is unplugged...this is because a capacitor never fully discharges.. However, I'm not sure if the comment above was made in jest, that is...

Homework Statement Consider two identical capacitors with parallel plates (the distance between the plates is (d). In each of them a metal (thickness d/3, surface equal to the plates surface) is placed right in between the plates. In one of them a metal part is connected to the upper plate, an...

I know that in the left circuit, current will not flow where the resistors are attached to the straight wire connecting A and B, but on the right one, current will flow where the resistors are attached to the straight wire x and y http://img824.imageshack.us/img824/880/this1p.jpg Is...

Homework Statement An isolated capacitor C1 carries a charge Q0. Its wires are then connected to those of a second capacitor C2, previously uncharged. What charge will each carry now? What will be the potential difference across each? Homework Equations C=Q/VThe Attempt at a Solution I figured...

My colleague and I have a disagreement about the storage of electrical energy using capacitors in DC circuitry. It all has to do with the equation for the capacitive energy storage, namely the energy stored in a capacitor with capacitance C charged from a power supply at some constant potential...

A capacitor is connected to a cell of emf 200V and fully charged. Another capacitor is then connected in parallel, which has 1/100th of the capacitance of the charged capacitor. The total charge is instantly shared between the two capacitors, and so the capacitor connected in parallel to the...

Hello everyone, I know this may be a very elementary question but I'm not an EE or have access to one other that this forum. I've been reading up on capacitors and so far I'm not able to decipher if a cap will discharge only if the capacitor has reached its maximum capacity. I would think...

I guess the title basically explains it. I'm reading over some circuits and can't figure out how to find total current for a circuit with capacitors in series.

Homework Statement hi guys, i just have some theory and general questions about circuits. hope you can bear with me and be able to help me out cause I'm trying to grasp the ideas. thanks! 1) i have a RC circuit that has a switch. if the switch was close for a long time and then opened...

what happens if AC is applied to a capacitor? I am able to understand that ,For 1st half of the cycle,i.e for +ve cycle, during the voltage rise from v0 to vpeak, the capacitor charges, and during the voltage drop from vpeak to v1 the capacitor discharges.Let me know if this is true. I...

I have a circuit that is in a read only file so I can't get an image on here so I will try to create it on here B-battery C-capacitor ----C1------------- l.....l...l B...C2...C3 l.....l...l -------------------- Ignore the periods (.) because they are just place holders. The...

I was looking up some information on series and parallel circuits, and a question popped in my head. I know that hooking up batteries and capacitors in series will give you a voltage equal to the sum of all the voltages in each component, but I was wondering why it does that?

When you need to couple ac signals you use coupling capacitors. How do we decide its value and what are the uses of coupling capacitors?

I have a question that is asking me to draw a diagram and explain the structure of different types of capacitors. I am actually not sure what they're referring to. Do you think they might be referring to types of capacitors like: Ceramic capacitor, mica capacitor, Electrolytic capacitor. The...

1-this is what is written in my book: E= Ir+E' where E' is the back emf, r and E' are constants P(mechanical)=E'*I an electrical motor functions only if the generator connected across its terminals delivers a positive potential difference that exceeds its back emf. So my question is, why are...

Hi, could anyone explain to me what the purpose of the each capacitor is in this common base colpitts?. C1,C1,L are used to set the oscillation frequancy, right? R1, R2,R3 are used to set the collector, base current and volatges, is that correct? So what is the purpose of C3, C5 and C4...

The question I had was more qualitative than quantitative, but I always preferred to understand concepts in both ways clearly. Can someone explain what happens to the capacitance of parallel-plate capacitor when a thick slab of metal is inserted between the plates, parallel to them but not in...

The question states: A charged capacitor C has stored energy U = 10.0J. A second, equal but initially uncharged capacitor (no energy stored) is then connected to the first in parallel. (a) What is the new net energy stored after the charge is redistributed? (b) Where did the excess energy...

Homework Statement Hi, I'm trying to find out are the capacitors in mutual capacitance touchscreens are in series or in parallel. I'm very confused because they're asking me what would happen if they were in parralel or in series? maybe in mutual capacitive touch screens they're in series...

If you can get any difference of potential across a capacitor of any capacitance, why it's better to use capacitors with small capacitance in some cases and capacitors with a big capacitance in other cases?

Hey. My textbook states of a capacitor that: "If one plate stores a charge +Q, then the other stores an equal and opposite charge -Q". I understand the electrons flow onto one plate and this excess of electrons causes the plate to have an overall negative charge which then repels...

Homework Statement An infinite array of identical 1-microFarad capacitors are arranged in a grid setup, where junctions are between capacitors, and each junction is connected to 4 other junctions separated by another capacitor. The array is initially uncharged. A battery is connected...

Hello, I am a first year undergrade currently taking elementary physics course in university. I have hard time understanding the concept of capacitors. Please correct me if I am wrong. 1. My understanding of capacitor is that it stores energy by setting up a voltage across and releases when...

Homework Statement C. What is the charge on each of the four capacitors if switch S is closed? I have the charges if the switch is open, C1 and C2 are 8μC and C3 and C4 are 6μC since charges are same on series. Homework Equations The Attempt at a Solution I know to find Ceq and...

Homework Statement Suppose that C1 = C2 = C3 = 16.0 µF and C4 = 28.5 µF. If the charge on C2 is Q2 = 12.4 µC, determine the charge on each of the other capacitors, the voltage across each capacitor, and the voltage Vab across the entire combination...

Homework Statement A 2.70µF capacitor is charged to 475 V and a 4.00µF capacitor is charged to 525 V. (a) These capacitors are then disconnected from their batteries, and the positive plates are now connected to each other and the negative plates are connected to each other. What will be the...

A coaxial cable used in a transmission line has an inner radius of 0.10 mm and an outer radius of 0.60 mm. Calculate the capacitance per meter for the cable. Assume that the space between the conductors is filled with polystyrene. Kappa for polystyrene is 2.6 I have no clue how to start or...

Homework Statement Let's say I have a circuit that looks like that below http://img262.imageshack.us/img262/9260/97438850.th.png Uploaded with ImageShack.us Questions Now I got two questions a) If the middle (the one in 180 degrees) capacitor were not there, would still...

Homework Statement The distance between two parallel plates is increased while they remain hooked to a battery. The energy stored in the capacitor will: AND The distance between two parallel plates is doubled while they remain hooked to a battery. The battery voltage also is doubled. The...

Homework Statement At t=0m the switch is open and both capacitors are uncharged. What are the charges on each plate (magnitude and sign) of each capacitor long after the switch is closed and capacitors are fully charged? Homework Equations q=C E(1-e^(-t/RC) The Attempt at a Solution...