Capacitor Definition and 1000 Threads

Hi , I'm in need for some 10+ caps for my smps secondary side smoothing. the thing is electrolytics are not cheap , so I need about 1000uF a piece but there is a big difference between whether it's 200v rated or 100v rated. the voltage across the each cap would be about 92v DC , I wonder would a...

Homework Statement Hello! I would like to check on my knowledge of bypass capacitor which bodders me a bit Homework Equations Is that true? The Attempt at a Solution Bypass capacitors are use to filter AC ripples. It does it in the following way: Let's imagine an RC amplifier. When the...

My textbook says this makes three pairs of parallel capacitors. I don't understand how?To make three pairs of parallel plates capacitors we at least need four plates but here we have only two

A 5μF capacitor is connected in parallel with a 2MΩ resistor and the combination is then connected in series with a 1MΩ resistor through a switch to a 12V battery. Find the time taken for the voltage across the capacitor to rise from zero initial value to 2V after the switch is closed.From what...

What happens when negative plate of a charged capacitor is connected to positive plate of another charged capacitor and vice versa. ?

Homework Statement I am currently trying to work on the extra credit question, the capacitance of the capacitor is 2 microfarads Homework Equations W = 1/2CV^2 The Attempt at a Solution I've done the previous sections, and have gotten 4.23 * 10^-11 J as the answer for the work done on the...

Homework Statement I am given the current flowing through a 2 micro-farad capacitor in the form of a graph, and I need to create a voltage graph from this. Homework Equations I = C dv/dt Q = VC The Attempt at a Solution The current graph is basic with a constant 4 mA from 0 to 4 microseconds...

Hi Experts, I'm preparing piezo electric generator project, but when I'm searching for piezo disc for my project, i came across different sizes of piezo electric disc, but i didn't found any datasheet, My question is what's the output voltage/power difference between different diameter...

Homework Statement A capacitor of capacitance 5µF is charged to 24 V and another capacitor of capacitance 6µF is charged to 12 V. The positive plate of first capacitor is now connected to negative plate of second and vice versa.Fid ew charges on capacitor. Homework Equations Q=CV E= QV/2 =...

A capacitor is connected to a battery. If a person pulls the plate to increase the distance by 2d the decrease in energy between the plates is E. We observe energy gained by battery is 2E. From where does extra energy E come from.?

If I am charging a super capacitor with buck converter, that is a 1 amp, 1-18 volt output, and the capacitor is rated for 2.5 volts, how do I stop the buck converter from feeding it more than 2.5 volts? When I attach the capacitor to my digital power supply, it starts charging, and the voltage...

If I have a capacitor and I maintain the potential difference between the two plates as I move them apart would I have to do any work (other than mechanical work) to move them apart? my logic tells be I shouldn't have to as I'm not doing any work again the potential field? Just wondered what you...

Homework Statement [/B] An electron is launched at a 45∘ angle and a speed of 5.0×10^6 m/s from the positive plate of the parallel-plate capacitor shown in the figure (Figure 1) . The electron lands 4.0 cm away. a) What is the electric field strength inside the capacitor? b) What is the...

I've been making coil guns out of a disposable camera's flash circuit recently, and when experimenting with the capacitors themselves I've come across some things I can't explain, so I hope someone else can. 1. SOLVED: My mistake (In order to make my experiments easier, in place of the...

I'm doing a project where I need to hand power one small, dc motor (1.5-12V) and charge a 1F 5.5V super capacitor, and then use it to drive another small 1.5-12V dc motor. Does anybody have any suggestions for motor specifications or circuit elements that will help me get the most efficiency...

I'm sure the inductor model, i.e. vL(t) = iL'(t)*L follows without directly from Faraday's eq. But even there, with Faraday's equation we think of the changing magnetic field as inducing the voltage in the loop, where in the model it seems the other way around, that is, the voltage increases...

Homework Statement How to find the energy stored in the capacitor in steady state in this circuit. Homework EquationsThe Attempt at a Solution I found out the charge on the capacitor in steady state using loop law and did energy stored = (Q^2)/2C. but its coming...

Homework Statement A capacitor 1 of 3nF is charged with 3 volts. When it is completely charged, we connect it to an uncharged capacitor 2 of 7 nF. Calculate the charge on each capacitor after they reach electric equillibrium. Homework Equations Q=CV The Attempt at a Solution my confusion is...

The question in textbook:- A 4uF capacitor is charged by connecting it to 200V supply.It is then connected to an uncharged 2uF capacitor.How much electrostatic energy of the first capacitor is lost in form of heat and electromagnetic radiation? My question is that why the energy must be lost...

When a capacitor is connected to battery then positive charge is induced on one plate and a negative charge is induced on another plate.Now what happens to the charges that are induced on opposite sides of each plate i.e. on plate with positive charge a negative charge would be induced on...

Please explain in detail how to derive formula for capacitance of spherical capacitor?

Hi folks, I need to get a super capacitor which will be charged by a car battery and then connected to let out a massive pulse. (Yes a bigger pulse than my 450CCA battery can give). But first I need to work out how much capacitance will be needed. I'm not sure of the formula. Thanks

Hi folks, Just looking for an explanation on capacitor principles. My understanding: A capacitor is made from two conductors ( which have the ability to hold charge) separated by an insulator. Therefore current cannot flow between the+ and - plates. Unless unwanted breakdown from excessive...

I thought any two concentric conducting spheres of radii a and b such that a<b form a spherical parallel plate capacitor.But according to my book A spherical capacitor behaves as a parallel plate capacitor if it's spherical surfaces have large radii and are close to each other. 1)it's spherical...

Homework Statement Calculate the capacitance of the parallel plate capacitor shown in the following figure,between points X and Y. Homework Equations ##C##=##\frac{Kε0A}{d}## The Attempt at a Solution Which capacitor has an area "A"? I will have to transform this into circuit diagram.

Homework Statement https://isaacphysics.org/api/images/content/questions/physics/circuits/capacitors/level4/figures/Circuits_potentiometer_capacitor_otp_2.svg PQ is a slide-wire of uniform resistance, and J is a moveable contact at some point along it, such that the length from P to J is a...

Homework Statement Here is the problem in question. The only values given are those shown on the circuit labels. We are asked to form a voltage equation using Kirchoff's voltage law with specific loops. We were NOT asked to solve the equations for the currents. Homework Equations Sum of...

Homework Statement Capacitor parallel plates separation $$d$$, potencial diference $$V_0$$, at the center there is a semi sphere of radius $r_0$. Find the potencial as function of position if $$d>>r_0$$ Homework Equations I think that relevant equation are Gauss Law The Attempt at a...

Homework Statement A parallel plate capacitor was lowered into water in a horizontal position, with water filling up the gap between the plates (gap d=1.0mm). Then, a constant voltage V=200volt is applied to the capacitor. Find the increment of pressure in the water between the gap. Homework...

Homework Statement What charges will flow after shorting of the switch (Sw) in the circuit below through sections 1 and 2 in the direction indicated by the arrows? Homework Equations Kirchoff's laws The Attempt at a Solution Initially, both capacitors will have a charge of...

Homework Statement The parallel Plates of a capacitor have an area of 2.00 x 10-1m2 a separation distance of 1.00 X 10-2 m and are connected to a 3000 V power supply. The capacitor is then connected from the supply, and a dielectric is inserted between the plates. We find that the potential...

Homework Statement find the charge on each plate given area is a and separation between two consecutive plate is d Homework Equations ##Q##=##C####V## The Attempt at a Solution I don't know how to proceed from here.

I was going through charging of capacitor .I did not understand one thing .Plates of capacitors are uncharged initially but when battery is connected to it ,(positive terminal of the battery is connected to the Plate 1 and negative terminal of the battery is connected to plate 2)electrons from...

Homework Statement Consider two capacitors ##C_1##=10μf and ##C_2##=40μFif the two are connected in series to a 9.0 volt battery What are the charges ##Q_1## and ##Q_2## stored on the two capacitors? Homework Equations ##Q##-##C####V## The Attempt at a Solution The capacitors are connected in...

Homework Statement Homework Equations Series: R_{eq} = R_1 + ... + R_n Parallel: R_{eq} = \left(\frac{1}{R_1} + ... + \frac{1}{R_n} \right)^{-1} Charging Capacitor: I = I_0 e^{-t/RC} Charging Capacitor: \Delta V_C = \varepsilon (1- e^{-t/RC}) Charge: Q = C \Delta V_C The Attempt at a...

So, I have made an experiment of a low pass filter, and made a bode plot out of it. My experiment was done 100 percent in Japanese and this means I cannot understand completely the experiment I have done. So, there is a statement there saying the higher the frequency of the input voltage, the...

Homework Statement My (practise) coursework is to test the equation 'V = Vo e-t/RC' and choose values of R and C so that the voltage across the capacitor falls to half in 15 seconds. I decided it would be too difficult and inaccurate to record the voltage across the capacitor every 5 seconds...

Homework Statement Two plates (area=s) charged to +q1 and +q2 (q2<q1)are brought closer to form a capacitor of capacitance C.The potential difference across the plates is 2. Homework Equations ##V##=##\frac{Q}{C}## The Attempt at a Solution [/B] I don't know how are these plates going to...

Homework Statement Homework EquationsThe Attempt at a Solution for #14, I remember a battery maintains the potential therefore, V should be constant; dielectric increases charge on plates and increases capacitance but I couldn't find an option that matched. The answer key says "d" but I...

Homework Statement What is the entropy change of the universe as a result of the following processes: (a) a 1μF capacitor is connected to a 100V electrochemical cell at 0°C, (b) the same capacitor after being charged to 100V is discharged through a resistor kept at 0°C? Homework Equations...

Physically, can someone explain why does not the voltage on the capacitor change immediatly? and why does not the current in the inductor also do? :smile:

Homework Statement Determine the conductivity of the insulator in a spherical capacitor filled with weakly conductive dielectric. Specific conductivity of the dielectric is λ, the dielectric permittivity ε. Ansver in book is ##\Lambda = \frac{4\pi\lambda}{\epsilon} \frac{R_1R_2}{R_1-R_2}##...

suppose i have a circuit,in which a capacitor and resistances are connected in series with a DC voltage source. then after a long interval of time we know that capacitor will have same voltage across its terminal as that of DC voltage source and no current flow in the circuit. so, can i say at...

hi guys This query comes about after the comment by BillyT in post#22 in this thread https://www.physicsforums.com/threads/energy-in-a-capacitor.840145/page-2 is what he is saying correct, or only for the very specific situation he is involved with and it doesn't apply to every day...

why is the formula of energy in a capacitor E= C x U^2 /2 I understand it mathematically, but I do not understand it if you apply it to a real situation. Is there anyone who can explain that?

I am doing my wrong project from school. Its basically a science fair but only for the students in the class. I came up with the idea to use piezoelectric plates to charge a capacitor that then charges one of those portable po charge a phone. I know I'm not the first one do this, but I do want...

Problem: When a dielectric slab is inserted between the plates of one of the two identical capacitors in Fig. 25-23, do the following properties of that capacitor increase, decrease, or remain the same: (a) capacitance, (b) charge, (c) potential difference (d) How about the same properties of...

Homework Statement The Question is here: imgur link: http://i.imgur.com/wIlUZMM.jpg Homework Equations U_c = \frac{\kappa \epsilon_0 A d E^2}{2} U_c = C \Delta V_c \kappa: dielectric constant \epsilon_0: permittivity of free space C: capacitance The Attempt at a Solution [/B] I...

In this video: exactly in the 7:05, the narrator says that is dangerous to charge the inductor and disconnect it of the circuit and that is necessary provide anoter path for the current flow. The same phenomenon happens with a charged capacitor too? Is necessary provide a path for a charged...

Homework Statement A circuit consists of a voltage source, voltage ##V## , a resistor, resistance ##R##, and a capacitor, capacitance ##C##, in series. (i) Show that the charge ##Q(t)## in the capacitor satisfies the equation ##R Q' (t) + Q(t)/C = V ##. (ii) Suppose that ##R##, ##C## and...