Capacitor Definition and 1000 Threads

[Mod Note: Thread moved from technical forum hence no homework template.] Okay so the image i uploaded only because of the cirscuit never mind the text to it. I don't understand things mathematicaly verry well. I like to have a good physical grasp on what is going on with the circuit. That...

If given a capacitor with stored charge, would its charge remain constant before and after it is immersed in a liquid (i.e. distilled water)? Why? I know that before immersion, the capacitance would be = (ɛAV/d), but would that be the same if immerged in distilled water?

Homework Statement A parallel-plate capacitor has a plate area of 18.5 cm2 and a capacitance of 4.8 pF What is the plate separation? The value of the permittivity of a vacuum is 8.8542 x 10-12 C2/N⋅m2 Homework Equations C = κε0 (A/d) The Attempt at a Solution 4.8x10-12 =...

If i connect 2 capacitors in series with an AC source ,and an output ,then how exactly will the phase vary with input source ? A single capacitor makes a 90 degree phase difference with the current,if I don't want that ,what steps can I can take to change the phase difference to 0 ?

Hi. I put the simplest case. A capacitor formed by two flat metal plates faced in the vacuum, with charges of the same absolute value in both plates. In this case, the electric field of the capacitor, in a static situation, has an energy expressed in the following way. E=\dfrac{q^2}{2 \ C} Now...

It is given that an uncharged capacitor is connected with a battery. Clearly, it gets quickly charged and flow of current stops in the circuit. What is the reason behind a charged capacitor in completely restricting the flow of current ?

Hi guys..i have got a question...suppose i connect an inductor to a dc source until it is fully charged..as soon as it gets full of magnetic energy,i disconnect it from the circuit..remember that it has magnetic potential energy..suppose an idiot like me opens up the inductor (as inductor is...

Hi, I am trying to understand capacitors and have come across the example in the attached image. What I would like to understand is how to calculate the electric field at some distance x within the capacitor. With x>>R , x<R and x=R . The image is of two circular disks as the...

Homework Statement What happens if the capacitor plates are pulled farther apart? Homework Equations C=Q/V=EoA/d The Attempt at a Solution The answer is that the charge stays the same, and the potential difference increases, which results in increased PE. I saw multiple explanations...

Homework Statement a) State the boundary conditions for the electric field strength E and electric flux density D at a planar interface separating two media with dielectric constants ε1 and ε2. b) A parallel plate capacitor with a plate separation d is filled with two layers of different...

Homework Statement A parallel plate capacitor is made of two flat horizontal conducting plates in a vacuum, each of area A, separated by a small gap. One plate carries a total charge 2Q, the other a total charge −Q. Find the surface charge densities on the four horizontal metal surfaces in...

Homework Statement This circuit is given: After the current has stabilized calculate: 1. The current through the voltage source. 2. The voltage and charge on each capacitor. While the circuit is active and the current is stable, the 4μF capacitor is disconnected from the circuit. 3. What are...

Ok, so I am am trying to make a homemade capacitor that is 4700pf and 15kv. polyester at 125 micrometers thick can withstand 15kv so were good. here is the equation i used C=ε0 K A / D Where C = capacitance, ε0 is epsilons constant, K = dielectric constant, A = area of aluminum foil, and D is...

Homework Statement Homework EquationsThe Attempt at a Solution The energy stored in the capacitor is ## \frac { CV^2 } { 2 }##. So, this much energy will dissipate as heat. Hence, the correct option is (a). Is this correct? It doesn't depend on the shape of the capacitor, right? I have...

Homework Statement A proton is released from rest at the positive plate of a parallel plate capacitor. It crosses the capacitor and reaches the negative plate with a speed of 50,000 m/s. What will be the final speed of an electron released from rest at the negative plate? Homework Equations...

Homework Statement Find the total amount of energy of a charge (q) initially at rest placed at the left plate of a parallel plate capacitor. The left plate is at V = 0, the right plate at V = V0 and the plates are a distance L apart. Homework Equations Etot = 1/2 mv2 + qφ(x). φ(x) = Vx/L The...

Homework Statement A capacitor has square plates of length a separated at a distance d. Dielectrics are inserted as shown in the figure. Find the capacitance Homework EquationsThe Attempt at a Solution [/B] I know that I have to integrate, but can't get an expression

Homework Statement Each plate in the figure has area a and separation d , end of battery is e find charge supplied by battery Homework EquationsThe Attempt at a Solution . each facing plate will have half the charge supplied by battery, but I am...

The question (and image) that are puzzling me are the same as in https://www.physicsforums.com/threads/two-opposite-polarity-charged-capacitors-in-series.723158/ It says that the capacitors are in parallel, but why? I can´t understand this point, and it certainly seems as if they are in series...

Homework Statement Find ##i(0^+) ## and ##i(t), t≥0^+## Homework EquationsThe Attempt at a Solution [/B] I'm having trouble finding the current through this capacitor. I tried using a KVL loop for ##t=0^+##, but I'm doing it incorrectly or something. Earlier in the problem I found...

Homework Statement https://imgur.com/i5jylxC Homework Equations I have to find the charge in each capacitor The Attempt at a Solution I don't know how can i start, can i use kirchhoff rule in each loop, using q/C when i go through a capacitor?

Homework Statement Select the correct expression for ##i_o(t)## for ##t≥0^+##. Homework Equations ##V(t) = V(∞)+[v(0)-v(∞)]e^{\frac{-(t-t_0}{\tau}}## ##i(t) = C\frac{dV(t)}{dt}## ##\tau = RC## The Attempt at a Solution I'm a bit stuck on this problem. Specifically, I'm not sure how to deal...

Homework Statement The initial voltage on the 0.5 microF capacitor shown in the figure is -20 V. the capacitor current has the waveform shown in the figure. https://i.imgur.com/P8jwI7s.jpg?1 How much energy is stored in the capacitor at t = 870 micro seconds. Homework Equations v(t) = 1/c *...

Consider a parallel plate capacitor formed by two plates of length ##L## and width ##d##, separated by a distance ##e##. There is a vacuum in between the plates. Let's note the capacitance of this arrangement ##C_0##. I insert a conducting plate of length ##l=L/2##, with ##D##, and thickness...

Homework Statement A parallel plate capacitor has 2 square plates of side l, separated by a distance d (l is a lot bigger than d). Between the plates, there is a linear and non-homogeneous dielectric with constant $$\epsilon_R=1+ay$$ with $$a$$a positive constant. Calculate the electric field...

Homework Statement In a lab experiment we measured the potential at different points within a cylindrical capacitor electric field modeling plate thing (apparently that's the best I could do to translate that into English). The positive electrode was connected in the middle and the negative...

Homework Statement Find the voltage across the capacitor given the data underneath the circuit. Homework Equations Voltage Divider Rule Thevenin Equivalent Ohms Law The Attempt at a Solution I have tried using the Voltage divider rule but I can't seem to get the right answer. The correct...

Homework Statement 1. The characteristic decay constant for a capacitor C discharging through a resistor R is the product of R times C. If the initial voltage at time t = 0 is Vo = 13Volts and what is the voltage at time t = 2RC? 2. A capacitor C = 9microFarads is charged from 0Volts to...

Consider a simple circuit consisting of a battery and a parallel plate capacitor .During the process of charging of capacitors, we come to learn that half of the work done by the battery is stored in the form of potential energy and half of it is lost as heat or electromagnetic radiation...

Homework Statement How long does it take in time constants ( = RC) for the charge on the capacitor in the circuit shown below to reach one quarter its initial value? Homework Equations C=Q/V time constant=RC Vc = Vo * (e)^(-t/RC) The Attempt at a Solution From C=Q/V I get Q=VC so for the...

Hello guys, came across some Analytical Physics lectures (http://www.physics.rutgers.edu/ugrad/227_f11/classes/lect08.pdf) that got me confused. It is described in the lecture the problem of determining the force between capacitor plates for a constant voltage (ie. connected to a battery). For...

Homework Statement Are ALL parallel plate capacitors linear? Homework Equations D = permittivity * E The Attempt at a Solution Capacitance is linear if permittivity is constant. Is there a case where a parallel plate capacitor is not linear?

Homework Statement A parallel-plate capacitor is charged to 4850 V. A proton is fired into the center of the capacitor at a speed of v0=2.81 * 10^5 m/s. The proton is deflected while inside the capacitor, and the plates are long enough that the proton will hit one of them before emerging from...

Hi, I am trying to figure out the peak voltage across a capacitor when charged by 1/2 wave rectified AC. The formula for instantaneous voltage is : Vc=Vs(1-e-t/RC) where: Vc=Capacitor voltage, Vs=Source Voltage, t=time RC = the capacitor time constant So I thought I could integrate with...

Hi folks, here's a thought/conceptual question I've been wondering about. What is the maximum theoretical specific energy (IE Joules/kg or equivalent) for energy stored in the electric field of a capacitor? I know the energy stored in a capacitor is given by U=C V^2/2, and the mass of the system...

Hi. As far as I know, the main reason for using AC in electric power transmission is that voltage can easily be transformed. If there was a similarly easy way for transforming DC, would power grids work basically the same? To be more specific, how much does AC power transmission rely on the...

Homework Statement We had a laboration for calculating ε_r in a parallel plate capacitor which we stuffed with plastic plates. All data we picked up was the area A, the distance d (and thus 1/d) and the capacitance C. We are now supposed to use the least squares-method to find ε_r, something we...

I'm trying to understand the difference between these two when it comes to measuring the amount of time they take. As of right now, my current understanding is that pole relaxation is based on the amount of time that it takes for polarization of the charges to go back to its relaxed state. For...

This question is from my physics book and neither I nor my teacher can find the mistake in my method. (The original question is not in English so I'll do my best translating it) > When a coffee maker is connected to the wall (230 V, 50 Hz) its power consumption is 180 W. The power consumption...

Homework Statement Two parallel plates of metal sandwich a dielectric pad of thickness d, forming an ideal capacitor of capacitance C. The dielectric pad is elastic, having a spring constant k. If an ideal battery of voltage V across its terminals is connected to the two plates of this...

Homework Statement Consider a circuit that consists on a resistor of an intrinsic semiconductor R and a capacitor C in series. The voltage between the terminals of the circuit is U, which is an alternated sinusoidal voltage. U1, which is the voltage in the capacitor as a phase difference of 30...

I want to calculate Electric field inside and outside a capacitor(two parallel conductor plates and in between a dielectric) which is fed by an AC voltage source. My problem is I do not know how can I relate the electric field to the potential in a capacitor. I got confused about the derivative...

hi, I wonder that inclined plate capacitor formula is the formula in last picture I shared? I am not sure because there are not enough examples about that ?

Homework Statement Homework EquationsThe Attempt at a Solution The force between the plates is given by (1/2)QE ,where Q is the charge on the plates and E is the electric field between the plates . Now Q = CV and E = V/d , where C is the capacitance , V is the potential difference and d is...

Homework Statement Determine the potential difference across the plates of the capacitor of the network shown in the figure. Homework Equations kirchoff's loop rule q=vc 3. The attempt at a solutio applying kirchhoffs law starting at bottom right point, q/c2-E1+q/c1+E2=0 =>E2-E1=-q/c1-q/c2...

All sites and books give different answers for this question:( Homework Statement predict the polarity of the capacitor in the diagram below Homework Equations right hand thumb rule AB is capacitor The Attempt at a Solution The side facing south pole becomes south and north facing side...

Hi, I'm trying to form an expression for a rectifier supplying a DC link with current, without actually rectifying a 3-phase input. Usage of the model is really only concerned with the RMS values and the active power drawn from the AC supply. The DC link is just a capacitor so that: dVDC/dt =...

Homework Statement Homework EquationsThe Attempt at a Solution I have difficulty in solving part (C). The surface bounded by the Amperean loop is like an open drum. The current enclosed by the loop is ## I_{en}## = I through the bottom of the drum + I(s) through that part of the curved...

Homework Statement Homework EquationsThe Attempt at a Solution Assuming the current is steady, I = JA, where J is the current density and A is the cross- sectional area ##E = J/\sigma## Can I take ##\sigma ## uniform here ?

Homework Statement Homework EquationsThe Attempt at a Solution A)Clearly, ##V_A - V_B >0 \\V_C - V_D >0## as the current flows from higher potential to the lower potential. As the time passes on, the potential difference across the capacitor as well as the resistor goes on decreasing...