Capacitor Definition and 1000 Threads

  1. M

    What do the numbers on a capacitor mean?

    The numbers seem to read 225 PC 330 4 What does it mean? Someone told me "225 = 22 x 10^5 pF = 2.2 μF" with 330 V being the potential rating "PC" = polymer cap Is this correct?
  2. K

    Capacitor Charge/Discharge boundary conditions for time

    Homework Statement Homework Equations 3. The Attempt at a Solution [/B] I know dV=1/C∫idt and that we integrate the voltage from V to V0. What I don't get are the boundary conditions for t - How do we get what we get in the parenthesis? My closest assumption is that the t/T values refer to the...
  3. R

    About capacitor -- how can current flow "through" it?

    Usually people get kind of frustrated about how can a capacitor charge up when there's no current flowing through, including me. Can I interpret the picture better by considering the electric potential set up by the battery across the circuit? Is this interpretation a correct one? Sorry for...
  4. E

    How many electrons on a Capacitor calculation

    Hello, How to find number of electronics in capacitor? as 1 coulomb and 1 Amp has 6.25x10^18 on what they depend? Is this correct..? Q=C*V C=47uF and V=12V Q=47*10^-6*12=5.64*10^-4 Coulmb?
  5. W

    Find Equivalent Capacitance Between A & B with Capacitor

    Homework Statement https://scontent-kul1-1.xx.fbcdn.net/v/t34.0-12/13228153_10206233880597531_197570509_n.png?oh=32466b5e1ab50b8c8a0f49be9d044411&oe=573C076F Find the equivalent capacitance between A and B Homework Equations Capacitor The Attempt at a Solution...
  6. Titan97

    Capacitor and inductor in parallel

    Homework Statement [/B] Find the power supplied by the battery. Homework Equations $$Z_C=-iX_C$$ $$Z_L=iX_L$$ The Attempt at a Solution $$Z_1=R_1-iX_C=\sqrt{R_1^2+X_C^2}e^{i\phi_1}$$ $$Z_2=R_+iX_L=\sqrt{R_2^2+X_L^2}e^{i\phi_2}$$ $$I_1(t)=\frac{V_0}{\sqrt{R_1^2+X_C^2}}e^{i(\omega...
  7. L

    Power supplied by capacitor bank

    < Mentor Note -- thread moved to HH from the technical forums, so no HH Template is shown > Hi, I have the following circuit, where V2 is found to be 0.964∠-3.3 (degrees) p.u. Then I am to find the reactive power supplied by the capacitor bank (j0.25 p.u, to the right). I got the right...
  8. Drakkith

    Charge on Capacitor in RLC Circuit

    Homework Statement At t = 0, the charge stored on the capacitor plates is maximum in an oscillating series RLC circuit. At what time will the maximum possible energy that can be stored in the capacitor fall to one-eighth of its initial value if R = 7.20 Ω and L = 21.0 H? The differential...
  9. S

    Are R3, R1, R2, and the capacitor in parallel?

    Homework Statement Please see under attempt at a solution for my question. Homework Equations V=IR V=Q/C The Attempt at a Solution This was a conceptual question about currents I got it correct. Just for my knowledge I was wondering if R3,R1,R2, and the capacitor were all in parallel. I...
  10. 7see

    Why we used capacitor in the fan ?

    One of my classmate asked me a question that Why we used capacitor in the fan ? I gave her the answer but she said the answer in not fully appropriate ! Any one give me proper explanation of this question ?
  11. M

    Graphing the energy in an capacitor, coil and resistor

    I need to graph the current energy on a resistor, capacitor and inductor they are all separate it is not a RLC circuit. This is what I know u(t) = sqrt(2)*220*sin(314*t+π/3) R = 10 Ω L = 3 mH C= 3 mF I have already calculated the current for each component, now I need to calculate the energy...
  12. lucasLima

    Help calculating the voltage in a capacitor when t->infinite

    Hello Everyone! So, I need to calculate the voltage in the capacitor, let's call it Vc(t). For t=0- I know that there is no current in the capacitor. Did some calculations and I've found that Vc(0)=6v. Now i need to know Vc(infinite) But when the switch key is opened and the time goes to...
  13. V

    Charged Capacitor: Opposing Emf Battery Series

    can a charged capacitor mathematically be represented as uncharged capacitor connected in series with battery of opposing emf ?
  14. GRASBOCK

    Capacitive touchscreen control using a transistor

    Hello, I'm posting the first time on this forum. I want to create a robot controlled by an Arduino which is able to make a touch signal without using a mechanic arm or finger ( here is a robot with the same goal but using an arm video). I want to take the electrical approach. A modern...
  15. P

    What exactly does the capacitor do in a Tesla coil?

    In all tutorials I have read on tesla coils, they have said to use a capacitor spark-gap configuration, to create a tank circuit. I want to know exactly what this means, and what is its purpose. I am not going to build a Tesla coil, I am nearly just interested in the science of it.
  16. I

    Potential Difference Across Capacitor Regions and Work Done

    Homework Statement A parallel plate capacitor of area A and separation d is fully charged so that the charge on the top plate is Q. The battery is disconnected and two dielectric slabs of dielectric constant k are inserted with an air gap between them. Each region takes up one third of the...
  17. Titan97

    Uncharged capacitor connected to a charged capacitor

    Homework Statement An uncharged capacitor is connected to a charged capacitor as shown: The ends are left as it is. Will the charges redistibute? Homework Equations None The Attempt at a Solution I think it won't. Let the first capacitor be charged with charge Q. Before closing the switch...
  18. S

    Capacitor and Dielectric: Charge, Arrangement, and Extraction Calculations

    Homework Statement A ##12 \mu F## capacitor ##C_{1}## consists of plates ##A## and ##B##. An ##18 \mu F## capacitor ##C_{2}## consists of plates ##C## and ##D##. (a) Each are charged up by a ##10 V## battery such that plates ##A## and ##C## are positively charged. They are disconnected from...
  19. kostoglotov

    Why are these capacitor voltages opposite polarity?

    Homework Statement imgur link: http://i.imgur.com/JETj0Cq.png Homework Equations V_L = L\frac{dI_1}{dt} V_L + V_1 + V_2 + V_{R1} = 0 The Attempt at a Solution [/B] Just using basic KVL, shouldn't V_L = -V_2 - V_1 - V_{R1} and so therefore we should get \frac{dI_1}{dt} = \frac{-V_2 -...
  20. NickTesla

    Capacitor Discharge Time Formula Euler

    I would like to understand how the Euler constant elevated to fractional exponent gave this result? 958mV someone please!?
  21. P

    Deriving Capacitor Voltage for a Discharging Capacitor

    Homework Statement I'm trying to derive the voltage waveform across the capacitor for a discharging capacitor that has been fully charged by a DC power supply ##v_0##, i.e. ##v_c(t=0)=v_0## and then at ##t=0## the switch is flipped and the capacitor starts to discharge. Homework Equations The...
  22. ReidMerrill

    Peak Voltage across a capacitor.

    Homework Statement https://session.masteringphysics.com/problemAsset/1385140/3/36.P42.jpg Part A What is the peak current supplied by the emf in the figure? Part B What is the peak voltage across the 4.0 μF capacitor? Homework Equations I = V/XC = E0/1/2πfC = 2πfCE0 The Attempt at a Solution...
  23. ReidMerrill

    Capacitor Peak Current and Voltage in an AC Circuit

    Homework Statement A capacitor has a peak current of 240 μA when the peak voltage at 250 kHz is 2.7 V . Part A What is the capacitance? Part B If the peak voltage is held constant, what is the peak current at 500 kHzHomework Equations Xc=1/wC Vc=IcXc The Attempt at a Solution I rearranged...
  24. R

    Time for capacitor charging in RLC circuit.

    Homework Statement In series RLC circuit how much time it takes for capacitor to charge to 0.63% of source voltage..? time constant is the time taken by a capacitor to charge to 0.63% of source voltage and in rc circuit time constant is RC. but what about for capacitor in series RLC circuit...
  25. Y

    Why does a capacitor discharge slowly?

    Homework Statement Explain why a capacitor will discharge, although very slowly when there is high internal resistance? Homework Equations V=IR Q=V/C The Attempt at a Solution I am confused slightly by internal resistnace. Does that refer to regular resistance. From that high internal...
  26. P

    Impedance of capacitor and inductors

    I do not understand how to solve capacitors and inductors with impedance. I do not even know what it is that they use it to solve for. My understanding is that the define the source as a sinusoid using the complex exponential form, and that all voltages and amperage are now also complex...
  27. P

    What Are These Two Equations for Equivalent Capacitor Circuits?

    I do not understand these two equations V[eq][/SUB] = V[in][/SUB] and R[eq][/SUB] = -(V[oc][/SUB] / I[oc][/SUB] ) Your help is much appreciated
  28. Planobilly

    Mallory 50V 2500uf large can capacitor question

    Hi guys, I am trying to replace two 1960's Hunts 50V 2500uf large can aluminum capacitor that are in a 1964 transistor Vox T.60 bass amp. The capacitor is about 4 inches long and 1 and 3/8 inches in dia. I see on ebay a Mallory 2500uF 50V Large Can Electrolytic Capacitor CGS252U050R4C3PH for...
  29. L

    Magnetic Field in parallel plate capacitor

    Homework Statement A parallel plate capacitor of area 60cm^2 and separation 3mm is charged initially at 90 micro coulomb. If the medium between the plates get slightly conducting and the plate loses charge initially at the rate of 2.5 *10^-8 C per sec then what is the magnetic field between the...
  30. R

    Conceptual question about capacitor plate size

    You have a capacitor and each plate is of area A, explain qualitatively what happens to the capacitance when you increase the size of only one of the plates and why. Edit: adding some conditions: 1. they are circular discs (for simplicity's sake) 2. one has diameter d1, one has d2, 3. make...
  31. Clancy John

    Charging a capacitor using a 4V solar panel

    Will a 4V solar panel connected to a 100V rated capacitor stop charging the cap at 4V or will the cap keep pulling ad infinitum? Seems like the capacitor has no knowledge of the notion "I am full so stop drawing current" else they would not get destroyed if the solar panel was 500V instead. I...
  32. Planobilly

    Help to identify a capacitor in this schematic

    Hi guys, I am working on a Marshal 1974X-20-20 reissue 18 watt tube amp hand wired point to point. http://www.ampwares.com/schematics/marshall/marshall_18watt_schem.pdf Capacitor C3 connected to the cathodes of the EL84's has a stated value per the schematic as 50-500uf/50V. The actual cap in...
  33. R

    Force of parallel plate capacitor

    Homework Statement A parallel-plate capacitor has a plate area of .3m^2 and a plate separation of .1mm. If the charge on ech plate has a magnitude of 5*10^-6C then the force exerted by one plate on the other has what magnitude Homework Equations Q=E Ԑ A F=qE The Attempt at a Solution so to...
  34. Drakkith

    Increase in Charge on a Parallel Plate Capacitor

    Homework Statement The charge on the 3.00 cm2 area plates of an air-filled parallel plate capacitor is such that the electric field is at the breakdown value. By what factor will the maximum charge on the plates increase when bakelite is inserted between the plates? (The dielectric strength of...
  35. recursive

    Capacitor Energy With Different Dielectrics

    Homework Statement Two parallel plates are connected to a battery which maintains a constant potential difference of 12.0 V. The distance between the plates can be varied and there are three plates of different dielectric materials available: rubber (0.40 mm, κ = 6.7), glass (4 mm, κ = 7) and...
  36. B

    Electric field between inner and outer cylinder

    Homework Statement A capacitor is constructed of two long concentric metal cylinders, each having length of 1.0 meters. The inner cylinder has a radius R1 = 1.0 cm, and the outer cylinder has a radius R2 = 1.25 cm. The hollow space between the two cylinders is filled with nylon having a...
  37. E

    Dielectric in a capacitor in equilibrium

    Homework Statement Consider the situation shown in the figure. The width of each plate is b. the capacitor plates are rigidly clamped in the lab and connected to a battery of emf E. All surfaces are frictionless. Calculate the value of M for which the dielectric will stay in equilibrium...
  38. K

    Build a Capacitor in 30 minutes

    Hi! I have to build a capacitor out of the following materials: 10 square feet of aluminum foil, 10 square feet of saran wrap (polyvinyl chloride), several sheets of paper, and tape to put it all together. I will only have about 30 minutes to manufacture my design. I have been researching...
  39. S

    How do Capacitors and Inductors Add/Remove VARS in AC?

    To my understanding, capacitors cause the current to lead the voltage which adds VARS to the circuit and inductors cause the current to lag behind the voltage which removes VARS (in AC circuits). Also, it is my understanding that VARS increase voltage. I work for one of the largest utilities...
  40. kostoglotov

    Understanding the Integration of i(t) to Find V(t) on a Capacitor

    Homework Statement imgur link: http://i.imgur.com/zGhum8Q.png The answer given in the back of the text is imgur link: http://i.imgur.com/hAprWPV.png Homework Equations v(t) = \frac{1}{C_{eq}}\int i_s dt The Attempt at a Solution I get the last piece of the piece-wise v(t) to be...
  41. G

    Calculating Charge on a Capacitor in a Circuit with a Switch

    For the circuit shown in the figure, the switch S is suddenly closed with the capacitor uncharged. After one time constant, the charge on the capacitor is closest to: a) 2.0 mC b) 0.74 mC c) 1.0 mC d) 1.3 mC e) 0.00 mCRelevant Formulas q = Q⋅(1-e-τ/R⋅C) τ = RC My Attempt q = Q(1-e-τ/T) q =...
  42. mattbeatlefreak

    Finding Minimum Plate Separation for Mica-Filled Capacitor

    Homework Statement You want to maintain a potential difference of 5000 V between the plates of a parallel-plate capacitor. What is the minimum value of the plate separation if the space between the plates is completely filled by a slab of mica? Homework Equations V=Ed (parallel plate...
  43. M

    Can I Design a Capacitor Bank without Any Previous Knowledge or Resources?

    im stuck on figuring out how to design a capacitor bank i have nothing to start with, its part of a project, and i want its input to be 12v (storage). im trying to google capacitor banks and trying to simulate my own using pspice but i keep getting floating nodes and missing resistors or...
  44. G

    How to select a smoothing capacitor?

    Im doing piezoelectric energy harvesting, with a circuit with full bridge rectifier, smoothing capacitor and resistive load. May i know how can i select a value of the smoothing capacitor for this situation? I read some article, they recommend 1000uF but didnt mention more information on why isit so
  45. neilson18

    Find an expression for the capacitor voltage

    Homework Statement [/B] An uncharged parallel-plate capacitor with spacing d is horizontal. A small bead with mass m and positive charge q is shot straight up from the bottom plate with speed v_0. It reaches maximum height y_max before falling back. Then the capacitor is charged with the bottom...
  46. Salvador

    Electrolytic capacitor voltage headroom

    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...
  47. H

    Bypass Capacitor: Filtering AC Ripples

    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...
  48. gracy

    Three dielectric slabs in a capacitor

    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
  49. N

    Kirchoff's Loop Rule Involving 2 Resistors and a Capacitor

    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...
  50. A

    Negative plate of a charged capacitor is connected to positive plate

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