Capacitors Definition and 868 Threads

Hopefully no one minds that I post a couple questions in a row as long as I'm following the rules: 1. Homework Statement Two infinite parallel plates labelled W and X are separated by 5.2 cm. The electric potential between the plates is 150 V. An electron starts from rest at time tW and...

Homework Statement Determine the charge on each capacitor and the voltage across ech, assuming C=3yF(micro) and the battery voltage is V=4.0...

Hi, I'm having a problem with this circuit finding potential difference between capacitors. I know the answers by playing around on simulation software A=12v B=8v and C=4v however, I am struggling to use the formula provided Vc= (Vt/Ct)*C to find the answers. It works fine in a parallel circuit...

Homework Statement You are building a parallel plate capacitor out of two square metal plates with side lengths of L and a thin piece of dielectric of thickness d and dielectric strength of Eb. The piece of dielectric will act as a means of separating the two metal plates. In terms of l...

Homework Statement Three capacitors of C1 = 6.7 micro-farads, C2 = 19.4 microfarads, and C3 = 9.3 microfarads are all connected in series to a 9 volt battery. The stored energy in C1 is found (U1s). The same three capacitors are connected in parallel to the same battery. The stored energy in...

Suppose we have a circuit with two capacitors connected to each other, C1 and C2. C1 is charged and has a potential difference of 5 V (V1=5V), but C2 is not charged (V2=0) Apparently it is known that the potential difference of these two capacitors will want to reach equilibrium. So V1=V2...

Homework Statement The switch is initially open and the capacitors are uncharged. The applied potential difference Vab = +210V. a.) What is the potential difference Vcd? b.) What is the potential difference across each capacitor when the switch is closed? c.) How much charge flowed through the...

Homework Statement The electric field between two circular plates of a capacitor is changing at a rate of 1.5 x 10^6 V/m per second. If the displacement current at this instant is Id = 0.80 x 10^-8A, find the dimensions of the plate. Homework Equations Id = ΔQ/Δt = ε0(ΔΦE/Δt) ΦE = EA Q = CV...

Conducting sphere A and B have different radii. A is charged upto Q and B is uncharged . Two spheres are connected via wire initially open.? Considering spereration between them large comparision to their size answer the following .. 1.> After the switch is closed for the first time the...

Homework Statement "A series combination of capacitors must always be smaller than the smallest individual capacitor." This is the statement that I am trying to validate, but I am stuck. Homework EquationsThe Attempt at a Solution [/B] I know that if you have a circuit that consists of a...

Hey PF, I have a thought experiment that's been driving me nuts, here it is: I take a parallel plate capacitor charge it up to a steady state and then isolate / disconnect it from the electrical system leaving me with two charged parallel plates. I then hook up a power supply to two corners of...

Homework Statement Connecting a capacitor in parallel in a rectifier circuit gives the following graph Homework EquationsThe Attempt at a Solution What effect will, adding a second capacitor in parallel with the first one and the resistor, on the graph? COuld you explain why it will have the...

hello! why capacitors and inductors affect the phase of both current and voltage of a AC circuit and resistors don't? let's say we have an AC circuit with resistors only, then there is no change in the voltage and current as imposed from the voltage/current source, right? but what happens...

Homework Statement A cylindrical parallel plate capacitor of radius R is discharged by an external current I. The total electric field flux inside the capacitor changes at a rate dΦe/dt = I/ ε0. What is the strength of the resulting magnetic field B(r, I) inside the capacitor at a radial...

Two capacitors with different capacitance are charged with two different voltages. When we connect both the capacitors with the similar terminals (that is positive terminal of one capacitor to the positive terminal of the other and vice-versa) the net charge is the sum of the former individual...

Hi guys, I'm new to this forum and I just started working on my first coilgun. I've watched several tutorials on how to build a coilgun but all the capacitors they use in the coilguns are electrolytic capacitors. The capacitors don't deliver as much energy as the car audio capacitors. I'm...

I would like to know if everything is good in my reasoning. I've never done exercises like that and I don't have the results. Homework Statement A generator which mantains a constant potential difference of 400V is connected to two capacitors in series C1 = 500pF and C2=1000pF. A dielectric is...

Homework Statement "Show that the variation of the potential between the plates of a large parallel plate capacitor remains the same if the air between the plates is replaced by a conductive medium." Homework Equations E = σ/ϵ0 ; C = ϵ0A/d ' C = Q/V ; E = -dV/dx ; R = ρl/A The Attempt at a...

Homework Statement Use either image charge method of separation of variables to solve: The distance between two large, grounded parallel conducting plates is 4x. Between them, two point charges +Q and -Q are inserted and have a distance x and 3x from one of the plates. (A line connecting the...

Homework Statement A capacitor of capacitance ##C_1 = C## is charged by a battery of potential difference ##V_0##. After fully charged, it is disconnected from the batter and reconnected in series to a second, uncharged capacitor of capacitance ##C_2 = C/2## and another battery of potential...

Homework Statement An electron with a speed of 5.0x10^6 m/s is injected into a parallel plate apparatus, in a vacuum, through a hole in the positive plate. The electron collides with the negative plate at 1.0x10^6 m/s. What is the potential difference between the plates? Vi= 5.0x10^6...

Homework Statement Explain what is happening in the following four circuits: I don't know how to draw the circuits, but they're really really simple: (a) Current source connected in a loop with an inductor (b) Current source connected in a loop with a capacitor (c) Voltage source connected in...

I've gotten myself in a bit of a muddle here, I'm hoping you lovelies can help me out! So, the capacitance relates to the amount of charge a capacitor can store. Higher capacitance, greater charge. Greater stored charge, greater stored energy (right? or not?). So a higher capacitance means you...

I want to know if my understanding is OK. If a capacitor is connected to a battery, the voltage across the capacitor will equal the battery's voltage, but this doesn't mean the capacitance is changing. The capacitance is a function of the capacitor alone (ignoring dielectrics). Right? If I...

im hooking up 6 450v 10000uf capacitors in parallel for an exparement for school (under supervision of my professor) he won't tell me how to monitor these devices and how to know when they are full and when to release them. does anyone think they could give me a quick and dirty answer?

Can someone provide for me a proof that the total energy of my equivalent capacitor is equal to the sum of the energy in all capacitors? Or, if this is untrue, tell me why? Is this applicable to current and resistors too? Thanks a lot.

Homework Statement A capacitor consisting of two concentric spheres is arranged so that the outer sphere can be separated and removed without disturbing the charges on either. The radius of the inner sphere is a and that of the outer sphere is b, and the charges are Q and -Q, respectively a)...

I feel so frustrated because I could not understand the basics of this topic. My teacher spent like 1 week trying to explain it. I understood the math of capacitors, but I could not understand what an electric potential is. For example, what do you really mean? when you have a capacitor and...

A capacitor is formed from two concentric spherical conducting shells separated by vacuum. The inner sphere has radius 10.5cm , and the outer sphere has radius 15.5cm . A potential difference of 110V is applied to the capacitor. What is the energy density at r= 10.6cm , just outside the inner...

Homework Statement Capacitors of 7.6 µF and 2.1 µF are charged as a parallel combination across a 333V battery. The capacitors are disconnected from the battery and each other. They are then connected positive plate to negative plate and negative plate to positive plate. Find the resulting...

Hi Folks. I am having trouble comprehending this and sounds like a contradiction. A capacitor will resist changes in current. A capacitor will pass high frequency ac. With a higher frequency alternating current the voltage is constantly changing so how is this possible if it resists change in...

I've found a problem about 2 identic capacitors which have the same voltage. One of them is sinked in oil and after that the 2 capacitors are connected in series. The problem ask for the for the energy variation. I've done the problem but I don't understand something: When the capacitors are...

Hello. So I'm trying to work on a project with capacitors. I have a twelve volt battery hooked up to a transformer that produces 120 v ac. I would like to then hook the transformer up to five capacitors in parallel and then use the power stored i the capacitors to shoot through my coils to...

First before asking the original question i need to make sure some of my concepts are correct: 1- what happens when a capacitor with its 2 plates having different areas is charged? according to this forum https://van.physics.illinois.edu/qa/listing.php?id=23409 as the long as the difference in...

Hi there. So here goes. I have been having issues with a replacement chiller unit that requires 230VAC single phase. An identical unit was running on 2 phases of a 110VAC 3 phase supply. I had a start capactior fail in this unit. When I connected the replacement unit, the compressor...

Homework Statement A ##240 nF## capacitor and a ##4.0 \mu F## capacitor are connected in series with a ##240 V## potential difference. The ##4.0 \mu F## capacitor has a parallel plate configuration, with a surface area of ##110 cm^2## and a dielectric material between the plates. The...

Hi PF. This isn't really a homework question so I posted it here. We were supposed to find a list of devices which we found used capacitors for homework but I had some questions about the capacitors I found in an old Del PC. I have attached the picture to this thread. There seems to be a large...

I'm having a brain fart so this is just another silly question but... when deriving the I-V relation for the capacitor: $$C=\frac{dq}{dV}$$ $$\frac{d}{dt}C=\frac{d}{dt} (\frac{dq}{dV})=\frac{d}{dt}C=\frac{di}{dV}$$ from here, normally we're supposed to do the following...

Why does the potential drops when charge pass through a capacitors connected in series.

First of all..I want to be clear about steady state..what actually it means..?? Does it mean state of constant current flowing across..? In my book..its written that in steady state current in inductor and voltage in capacitor is zero , hence energy consumed is zero fotr both in steady...

Homework Statement This is the circuit diagram I am working with: There is actually a switch under C3 that I didn't draw. Initially, the switch was set so that the red dashed line was part of the circuit and the green dashed line was not (so C1, C2, and C3 charged but C4 did not). Then...

Hello, I thought I had questions concerning Kirchoff's rules down to a tee, but now capacitors have entered the scene and I'm stumped. Homework Statement The circuit in the drawing (attached) shows two resistors, a capacitor, and a battery. When the capacitor is fully charged, what is...

Why exactly is it that a spark is created when capacitors are shorted? Even with a few volts capacitors will spark when shorted, with my limited somewhat basic knowledge this has puzzled me. Any help is greatly appreciated.

Homework Statement How to find out the equivalent capacitance using delta star conversion? Homework Equations Delta star conversion formula of capacitors The Attempt at a Solution Using the formula of resistors but not coming.What is the formula of delta star in capacitors?

Homework Statement (a) The separation between the plates of a parallel plate capacitor is 2 mm and the potential difference between them is 45 V. Find the electric field between the plates. If the permittivity of the dielectric medium between the plates is 20 \epsilon0, find the charge...

How come an insulator is put in between two capacitors? I realize it is to polarize the atoms and create a smaller electric field and hence smaller electric pressure/voltage and increase the capacitance. But why not use a conductor? Pretty much all the charge would cancel. OR am I missing a...

Doesn't this imply their voltages are the same? Why does my textbook say v= v1+ v2 ... Am I missing something here? Someone elucidate please .. And one more question... Is there any reason when using gauss's law why you use an upright cylinder in an infinite area and a...

Difficult Introductory Electricity Circuit Problem -- Capacitors Homework Statement The Attempt at a Solution This problem was very difficult, and the most I could do was re-arrange the circuit into a make-shift Wheatstone bridge with all capacitors instead of resistors/voltmeter...

what is the function of the cap 104, why is it there? what's the function of this cap in the dynamo.. i know caps are used in motors for P.F correction, but what about the dynamos in toys??

When a batter is charging, let's say 3V battery.. when it's full, does it stops there or continues to take in charge? Like for example, capacitors charges up, until it reaches the voltage which was charging it, when both becomes equal, the cap becomes open circuit.. i wonder if batteries also do...