Capacitor Definition and 1000 Threads

Hi, on page 23 of this datasheet (http://www.fairchildsemi.com/ds/LM/LM7805.pdf) the top figure 10 shows a setup for a fixed output regulator, for example suitable for logic chips which need a steady 5V. I was wondering how critical the values of capacitance were for C1 especially and also C0...

dear experts i connected several capacitors in series . their initial voltages are different. some were at 2.5v and some at 1v. Connected them in series, the volt differences remained. i am not sure why the voltage from to higher potential capacitor does not get.spread.across all tye...

Hello all, I am new here. So you see where my lack of understanding comes from; my background is as a Mechanical Engineer and I'm currently in my masters year. I haven't touched electronics since A levels but I was hoping somebody could point me in the right direction. These forums tend to...

In 1. (see attached), a is attached to ground, so has a voltage of 0 V. The voltage at b is -1 V, so the voltage across the capacitor (Vb-Va) is -1 V. My understanding is so rusty... What happens when a is now wired to the positive end of a 1.5 V battery, and the negative end of the battery...

Homework Statement See the image: http://postimg.org/image/q550yqqd1/ Left click to enlarge... Homework Equations For a parallel plate capacitor, Capacitance C=KεoA/d A is area of plate and d is distance between the two plates.. The Attempt at a Solution I do not know how...

Hello, In a MOS capacitor or MIS after applying a voltage on the metal, the valence band and the conduction band bend downwards (in the usual band diagram) when a positive voltage is applied. (p-type semiconductor). When the voltage is large enough, electrons forms an inverse layer(green)...

Homework Statement It would be greatly appreciated if someone could check over my work. It is very likely that I made mistakes. If I made any mistakes, could you please tell me where I went wrong? Thank you. I will use this problem to study for my next exam. I have also attached a...

At resonance (## \omega_0^2= 1/LC##) in an LCR-Circuit the phase angle given by \theta=\tan^{-1}\left( \frac{\omega L - 1/\omega C}{R} \right) obviously is zero. And still there are other phases to deal with. This I don't understand. Let me elaborate. For example when calculating the amount...

Homework Statement A circuit contains a single 250 pF capacitor hooked across a battery. It is desired to store three times as much energy in a combination of two capacitors by adding a single capacitor to this one. How would you hook it up, and what would its value be? Homework Equations...

What is the difference between a capacitor and a battery? As far as I have browsed, the most common answer found is capacitor discharges faster than a battery. Would anybody elaborate it in a clear way.

Homework Statement An electrode with a varying voltage V = V0 + VACejωt is placed near a plate. The current output from the electrode is then measured. We want to find the relation between the current output and the amplitude of vibration. We can assume VAC is small relative to V0...

Hi all, So I created this account specifically to get some clarification on capacitors. I've been reading alot, but can't seem to find any info on whether a resistor is essential in series to discharge a capacitor. Think of the simplest circuit possible that switches between a battery to...

Homework Statement the separation of a parallel plate capacitor is 2mm with a potential difference between them of 45V. (i) Find the electric field between the plates. (ii)Find the charge per unit area of the plates if the permittivity of the dielectric medium is 20 \epsilon_0 (iii) Find...

Hi, An electronics newbie here.. I'm trying to produce sound using a 555 timer. When I tried using the schematic(attached file), a definite sound came. But when I removed the capacitor C2 in the circuit, the sound (amplitude) actually increased! Why does this happen? Why then, do we use a...

I am in process of designing a homemade capacitance sensor and I'd like to have an approximation of the resulting capacitance of the following geometry. The plates are placed on the outer surface of a food grade plastic cylinder. The distance z between their edges is many times smaller than the...

Homework Statement The space between the plates of a parallel plate capacitor is completely filled with a conducting slab.What is the capacitance of the system ? Homework Equations The Attempt at a Solution The capacitance of a capacitor when a dielectric medium is placed...

I am building an LC-circuit. I was wondering what power of capacitor and loops of coil would be best to use to create a change in flux, which was not to big but could be detected in a range of 2 meters from source. A range of coils would also be nice as I will have it as a variable in my experiment.

Homework Statement The space between the plates of a parallel plate capacitor is filled consecutively with two dielectric layers of thickness d1 and d2 respectively.If A is the area of each plate,what is the capacity of the capacitor? Homework Equations C=\frac{εA}{d} (for parallel...

Homework Statement Calculate the Y parameters of a capacitor in parallel (see the attached figure). Homework Equations Y-Parameters: I_1=Y_{11}V_1+Y_{12}V_2 I_2=Y_{21}V_1+Y_{22}V_2 Y_{11} = \frac{I_1}{V_1} when V_2=0 Y_{12} = \frac{I_1}{V_2} when V_1=0 Y_{21} = \frac{I_2}{V_1}...

Homework Statement Dielectric medium inside capacitor consists of two types (check the pic). Capacitor's plates are connected to a source of constant tension U. Distance between the plates is d and their area is S. Find the electric charge of capacitor's plates. Data given: U=500 V, d=2cm...

Homework Statement Compute the equivalent capacitance for the network between points A and B.Homework Equations 1/(Ceq) = 1/C1 + 1/C2 + 1/C3... (series) Ceq = C1 + C2 + C3... (parallel) C1 = 6.9 nF C2 = 4.6 nF The Attempt at a Solution I have been getting stuck on a lot of these questions. A...

Say you have a charged, parallel plate capacitor, isolated from any external circuit. If you were then to gradually separate the two plates (or thicken the dielectric) what would happen to the charge on the two plates ?

How do test a power capacitor?

Hi, I have just seen this statement in another forum: An inductor is a constant current source for a limited time until its energy is expended. A capacitor is the counterpart being constant voltage until its energy is spent. I am not quite understand it. Can you help me? This is not a...

I saw this section somewhere in the forum: Picture 2 plates charged to a voltage V, w/ capacitance C. Of course Q = C*V. An electron is placed in between the plates & released, & it moves towards the positive plate. Said electron with its negative charge now adds to the positive charge...

Homework Statement Find the electric field in a capacitor with dielectric constant ε, then calculate the capacitance. For a parallel plate capacitor, two methods are usually offered. (M1) Add the electric fields from two infinite charge sheets, one with surface charge density σ, the other...

If we have a circuit (see attached) will our voltage source's supplied voltage be delayed by the capacitor in anyway? (as the voltage across a capacitor lags the current through a capacitor by 90 degrees) then, as the resistor,voltage source, and capacitor are all in parallel does this cause the...

Homework Statement A capacitor is charged by connecting it to a suitable battery. (a) Does the amount of energy stored in the capacitor increase, decrease, or remain the same if a dielectric is inserted while the capacitor is connected to the battery? Explain your answer. (b) Does the amount...

I have been hearing about the possibility of a graphene super capacitor for quite some time now, but it still seems they are not readily available. Is there anyway for me to get my hands on one? Would it be possible for me to buy/make one practical enough to replace a AA battery? What size...

Is it necessary that the conductive plates and the dielectric should be of same metal type in a electrolytic capacitor? For example if anode and cathode plates are silicon, the dielectric also needs to be SiO2. or what if the anode and cathode plate are of different metal type??

Homework Statement a capacitor of capacitance 10μF is fully charged to form a 20v d.c supply 1) calculate the charge stored by the capacitor 2) calculate the energy delivered by the 20v supply Homework Equations 1/2 cv2 The Attempt at a Solution 1) q =cv Q= 2x10-4 i don't...

Hi I was about to fall asleep last night and was thinking about breakdown voltage, when electrons are pulled from the surface of a conducting plate and form a channel that discharges a capacitor. This is called a vacuum arc, some other keywords are thermionic emission and work function...

I need to determine the capacitance for a capacitor that I will be connecting in series with a DC series motor to control the current drawn from the battery by the motor. How should I proceed? I have attached the schematic.

Homework Statement Find the transfer function, Vout(s)/Vin(s) The (s) signifies the laplace plane Homework Equations The Attempt at a Solution I'm keenly aware there is an error here (at least from comparing with the answer sheet). Can you tell me where I went wrong?

Homework Statement I'm almost embarrassed to post this, but insofar none of my searches online have yielded any results. My question is simply, given a parallel plate capacitor (for the purpose of simplicity let's assume that there are no edge effects) whose constituent plates have charge +aQ...

If you have an infinite non-conducting plate, the electric field just outside is equal to sigma / 2*epsilon. The electric field just outside a conductor is equal to sigma / epsilon. I understand both these results, but why is it than in the formula for the capacitance of a parallel plate...

Homework Statement A capacitor is charged up to it's maximum charge capacity. Once it's reached it's maximum charge capacity, a switched is open which isolates the charged capacitor in a circuit of it's own, containing itself and a resistor (The emf used to charge the capacitor is no longer...

If we imagine a simple circuit with a battery and a capacitor with negligible internal resistance, the capacitor is charged up to a point where the voltage it stores is equal to the voltage of the battery. The battery has supplied an energy equal to V*I*T (voltage times current times time)...

I have read, analyzed and researched so much, my eyes and mind are on a breaking point , therefore, what I really want to know , how and why.. is perhaps best summoned in what I really want to do in the end. So let's cut to the chase: I just simply want make a HV capacitor...

Homework Statement Find V(a) as a function of time in the following circuit when the switch is opened. Originally, the capacitor is charged to Vc = 1/101 * V1. The Attempt at a Solution I know that when the switch is opened, the capacitor is going to get charged again, and V(a) is going to...

I have read that if we have an isolated positively charged conductor, we can increase itself capacitance by bringing an identical conductor close to it and then earthing it, so, that the second conductor develops a negative charge and thereby helps in reducing the net electric potential on the...

Homework Statement For the multi-loop circuit as shown, assuming the capacitor is initially uncharged, find the currents in each of the resistors at t=0 after the switches are closed. So I believe there are 8 unknowns really because of the 8th branch with the capacitor. If you look at the...

Lets say if i got RC series circuit. If i increase the voltage supply frequency then what happen to the voltage across a capacitor ?? I rekon the voltage going to increases and the I going to decrease to negligible.

Hi, Consider a charged capacitor connected to a an empty capacitor. The charged capacitor starts to discharge while the empty capacitor starts charging. The whole process finishes when the two capacitors maintain the same potential difference. The problem is that when calculating the energies...

How does one go about 'compressing' a capacitor system? -------| 1 |--------| 2 |----------| 3 |------------------------ | | | |...

On conductive spring with constant k a plate o capacitor with mass m and surface S is hanged. It hangs x_{0} above the second fixed plate. Determine average distance, frequency and max amplitude of distance between the plates in case of U(T)=Asin\omega t. Say that capacity of capacitor is...

Is there a difference between these two things or is an electrolytic cell just a larger version of an electrolytic capacitor?

Homework Statement Two plates of equal area: length b, width w On one side, the plates are a distance d away from each other, on the other side, a distance d+a Homework Equations No equations given. Using E= kq/r^2, V=-∫E*dl The Attempt at a Solution E = kq ∫∫dxdz/(x^2 +...

A charge Q is kept at a distance x from one of the plates of a parallel capacitor having plates d distance apart with cross section area A.The whole system is earthed.Find the value of induced charges on both the plates. I tried putting the sum of induced charges equal to Q and balancing...

Homework Statement From the circuit find the impedances of the capacitor and inductor Is(t)=15 cos(500t) A Homework Equations The Attempt at a Solution So is this right? Convert the 15 cos 500t into polar form, 15<0 I. Then the resistor is 8 ohms, so 15*8 = 120 V...