Capacitor Definition and 1000 Threads

Homework Statement A capacitor is made of two parallel plates of area A, separation d. It is being charged by an AC source. Show that the displacement current inside the capacitor is the same as the conduction current. Homework Equations Idisp = ε(dΦE/dt) Q = CV C = Aε/d Xc = 1/(2πƒC) Q(t)...

Homework Statement A problem of practical interest is to make a beam of electrons turn a 90∘ corner. This can be done with the parallel-plate capacitor shown in the figure (Figure 1) . An electron with kinetic energy 2.0×10−17 J enters through a small hole in the bottom plate of the capacitor...

Homework Statement http://imgur.com/a/TOUjV part b, specifically finding the maximum charge for C1. The question that boggles me is whether Imax changes on the left side of the circuit, after the switch closes. Homework Equations V=IR Xc = 1/(wC) XL = wL The Attempt at a Solution I was able...

Homework Statement Three capacitors, with capacitances C1 = 4.0 μF, C2 = 3.0 μF, and C3 = 2.0 μF, are connected to a 24 -V voltage source, as shown in the figure. What is the charge on capacitor C2? http://imgur.com/x4LpU3t http://imgur.com/x4LpU3t a) What is the equivalent capacitance of the...

Why does capacitor charges up to full voltage as the emf of the battery even if there is a resistor is connected in series? I know that having a resistor means it will take longer to charge the capacitor but shouldn't some energy need to be lost in the resistor as well?

I don't understand this part. When the inductor is charging, the capacitor current should be decreasing because its supplying the load. When the inductor is discharging (after DT), the capacitor should be charging and hence the current should be increasing, but in the figure its decreasing, why...

Homework Statement 2 large plates are separated by a distance d and a space charge of uniform charge density p is placed between them and a potential difference V is applied across the plates. Find the electric field stength at a distance x fromt the positive plate The answer is -V/d...

Homework Statement There are three capacitors C1 = 2 uF, C2 = 4 uF, C3 = 6 uF. Each of these capacitors were connected to 200-V voltage source so every capacitor has been fully charged. Then, the three capacitors are connected like the image above. When S1 and S2 are closed, but S3 is...

Question: If you charge a capacitor circuit and then separate the capacitor, does voltage increase beyond the initial source? It seams counter intuitive that if you plug a 9 Volt battery into two metal plates and pull the plates apart that you'll get massive voltage spikes, but that's what the...

Let's say a switch causes a capacitor to charge and the switch opening causes the capacitor to discharge from its positive plate through a common ground to its negative plate. This common ground is connected to other components, if there is a difference in potential in other components to the...

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 51000 m/s . What will be the final speed of an electron released from rest at the negative plate? Homework Equations...

Homework Statement I'm fairly new at breadboards and I've tried to set up how I think it should be (BUT I've used a resistor instead of the second capacitor since I didn't have any on me at the moment AND I will be replacing it with a capacitor when I get the chance but just needed to see if...

Hi folks, this is not an actual HW question, but rather one of personal interest. I'm basically trying to understand your classic idealized parallel plate capacitor, but moving face-on through a plasma. 1. Homework Statement We have a diffuse neutral plasma made of free protons and electrons...

Hi. Inductance and capacitance have many analogies, both conceptually and formally. A capacitor connected to a voltage source carries the charge ##Q=C\cdot V##. The analogous equation for inductance is ##n\cdot \Phi=L\cdot I##. Charge is physical, it's proportional to the number of excess...

Homework Statement [/B] Derive an expression for vc(t) in the circuit of Figure P4.13 and sketch vc(t) to scale versus. I attached a screen shot of the circuit for this problem. time. Homework Equations V = IR V = V0exp(-t/tau) The Attempt at a Solution [/B] I am trying to find the...

Hi all, I have a question about charging a meta plate or a piece of metal with a capacitor. I need to charge a plate to negative or positive and search for some methods. I know charging by Conduction, Friction and Induction. I would like to use another method. I want to charge a capacitor (E.g...

Trying to build a simple 9V power supply using a 7809 voltage regulator and full wave rectifier. The load current from the regulator is 1A. So I = C*dv/dt, therefore, C = I*t/(delta V) To my understanding t is the time between the two peaks or the time the capacitor supplies the load. So if...

Homework Statement Hello everyone , this question has been troubling me for weeks,so if anyone could please help me out.i have attached the pic of the question.The answer given is 2 seconds but i am getting a different answer. Homework Equations first of all i distributed the charge on the two...

How does it work? I mean I know all the stuff, there is difference in potential and the charges flows, my question is, does the negative terminal of the batteries suck charges or the charges flowing to the negative terminal are flowing because they are pushed by the charges induced on the plate...

Homework Statement A parallel-plate capacitor is connected to a 100 V battery until it is fully charged. The distance between the plates is d and the space between the plates is filled with air (k=1.0). Then, the battery is disconnected. If the distance between the plates is increased to 3d...

Homework Statement Two 10-cm-diameter metal disks separated by a 0.64-mm-thick piece of Pyrex glass are charged to a potential difference of 1100 V . What is the surface charge density on the disks? What is the surface charge density on the glass? Homework Equations C=(e_0A)/d C=Q/V charge...

Homework Statement [/B] ##E_1=6V## ##E_3=5V## ##R_1=150Ω## ##R_2=R_3=100Ω## ##R_4=50Ω## ##R_5=300Ω## ##C_1=1.5 mF## ##C_2=0.5mF## Text: In the first condition when the switches 1 and 2 are open the capacitor 2 has charge on it. First the switch 1 closes and the charge flow of ##q_1=1 mC## is...

There's a force F between oppositely charged parallel plates. If the plates are free to move, they accelerate towards each other with acceleration a. If the plates are large and close to each other, we can reduce the mass of the system by moving the plates closer to each other, while keeping...

Homework Statement [/B] My question is regarding part C of the question. Homework Equations V = IR V(t) = V(1-e^(-t/tau)) The Attempt at a Solution My idea is to use Kirchoff's Voltage Law and find the voltage of the capacitor as a function of time, then since the voltage across capacitor is...

Homework Statement The circuit has been completed for several minutes. Suppose that ε = 55 V . Calculate the magnitude of charge on the 100 μF capacitor plate. Homework Equations Q = C * V The Attempt at a Solution Since the capacitors have been fully charged, current has stopped flowing at...

Homework Statement Normally this style of question wouldn't be too bad, however the 2 different parts confused me. Surely once set to a potential V, it would stay at that potential - it doesn't need to stay connected How are the 2 parts any different from each other?

Homework Statement In the circuit shown in the figure below, the hase difference between the current and the voltage is 30 degrees, show how could you verify the capacitance of the conductor so that the phase difference could be 15 degrees. Homework Equations tan θ=-Xc/R (the phase difference...

if a capacitor is connected to a battery and then it is fully charged . then a dielectric slab of k is inserted in the capacitor while the battery is still connected SLOWLY my question is will there be any heat produced?? my approach -- after insertion of dielectric , the charge on the...

Homework Statement This is a problem from some textbook a friend emailed me: The text goes like this: When the switch is open the charge on ##C1## equals ##Q_o=40uC## and ##C_2## has no charge on it. The switch closes and some charge ##q## flows through the capacitors (suppose the flow to be...

This is my first post and am curious if anybody here has any experience or advice on how to discharge a capacitor bank with 6 1F capacitors connected in parallel. I built a electric hybrid (basically electric transmission) vehicle that uses a 31hp gas engine to power a 23kW (peak) DC generator...

Homework Statement Two 2.4-cm-diameter disks face each other, 1.9 mm apart. They are charged to ± 12 nC . What is the electric field strength at the midpoint between the centers of the disks? Homework Equations The Attempt at a Solution Q=12*10^-9 A= Pi * r^2 = pi*(.012)^2 Q/A=...

Homework Statement "We will concentrate on the time taken for the capacitor to discharge to exactly one-half of its p.d, and how this varies with the value of the resistor. So repeat the experiment with different recorded values of R, and find the corresponding T, the time taken for V to fall...

Homework Statement This is the second problem from our test preparation cycle and i partially solved and understood it. The circuit in the picture is in the state of switch being open (STATE 1: SWITCH OPEN). Calculate ##E1## so that the change in the electrical energy of the capacitor is...

Homework Statement The time for which the diode conducts is Homework Equations Using integration and differentiation Vc = 1 / C integral (current)(dt) The Attempt at a Solution Vs = -Vc Vm sin(wt) = -Vc = - (1/C) integral (Idt) now differentiate both sides to get expression for I that is...

hey, so I learned about capacitors and one particular detail about capacitors that is stressed upon is that the field of a capacitor is contained between the plates of it( assuming the field from the edge of plate to be very small). So my question was that when we short a capacitor, why does the...

Homework Statement for the opamp circuit give in the figure, find Vo(t) for t > 0 the figure is attached. Homework Equations I know that tau = R * C that is the time constant of a capacitor discharging is equal to the product of the resistor that it discharges through and its capacitance.The...

I have a doubt on this calculation of magnetic field in presence of displacement current. Consider a capacitor of radius ##R## and with plates at distance ##d## being charged: there is a displacement current in it. Suppose that I want to calculate the magnetic field ##B## at a distance ##r <...

Homework Statement From the circuit diagram ( http://postimg.org/image/lldnr7mf7/ ) calculate the net charge flown through the capacitor 2. Homework Equations 3. The Attempt at a Solution [/B] I actually don't need to solve the full problem as i understand how, what i have trouble with is the...

Is the "Voltage variable capacitor" described in patent US 20070242410 A1 a commercially available component? Has anyone heard of this method of changing the dielectric constant using a biasing voltage? It has been nearly 13 years since the patent was filed, but I've never heard of it. It would...

Homework Statement Homework Equations 3. The Attempt at a Solution [/B] First i found the voltage ##U_{13}=\frac{E(R2+R3)}{R1+R2+R3}=50V## Then i figured that the charge on 1 and 2 is equal since the voltage across is the same right? ##Q1=Q2=U_{13}\frac{C1C2}{C1+C2}=80mC## and...

Homework Statement When the capacitor driven by DC voltage ##V_0##,it has the electric field distribution ##f(x,y,z)## When ##V=V_0e^{iwt}##,how to show the EM travel in the space forever like the light? Homework Equations ##-{\nabla}^2E-u{\epsilon}\frac{{\partial}^2{E}}{{\partial}t^2}=0...

Homework Statement In the circuit below (drew it the best I can) the switch is opened, how much time elapses before the capacitor loses half of its initial stored energy.Homework Equations [/B] q(t) = Qe-t/RC U = q2/2C The Attempt at a Solution [/B] So first thing I did was I set (1/2)Q2/2C...

Homework Statement The circuit in the figure below has been connected for a long time. Let R1 = 8.20 Ω and R2 = 4.40 Ω. (a) What is the potential difference across the capacitor? (b) If the battery is disconnected from the circuit, over what time interval does the capacitor discharge to...

Homework Statement there's a paper insulated plate capacitor. a.) What should the area of the plates be when the capacitance is 0,1 μF. thickness of the paper in between the plates of the plate capacitor is 0,05mm the relative permittivity of the paper is 2,5 b.) How big of a charge can be...

Hallo, I have a question which elements are responsible for the increase of tangent delta in a X Capacitor and the reduction of its insulation resistance?

Homework Statement In the circuit of the figure below, the switch S has been open for a long time. It is then suddenly closed. Take = 10.0 V, R1 = 56.0 kΩ, R2 = 200 kΩ, and C = 14.5 μF. (a) Determine the time constant before the switch is closed. (b) Determine the time constant after the...

Hello, I am designing a phone charger with super capacitor with capacitance C=100F. The max voltage of cap is 2.7 V. When I charge the capacitance and then charge my phone, it is charging really slowly with low current (around 700mA). However, as I read, capacitance should output high current...

Homework Statement I am practicing these types of problems, for example: and I am asked to find i(t) in this case, and it is in steady state. I really need someone to walk me through these types of problems, how do I get them started. Homework EquationsThe Attempt at a Solution I am really...

HiI’ve been reading for a while and decided to ask , suppose we have a parallel plate capacitor with a distance x between the plates , in between the plates are another two plates with a dielectric so in total 4 plates. The outer two are attached to a dc supply of 12volts for example. Now I...

Homework Statement Plate capacitor is filled with two dielectrics of constants 3 and 4, and with a metal as seen in the picture. If the el. field in the first dielectric is 30 kV/cm, do: a) diagram of el. potential difference with calculated characteristic values using point C as a...