# Questions tagged [capacitance]

The ability of an object to store electric charge.

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### Repulsive force from charge accumulation in a capacitor plate?

During a charged state of a capacitor (Regardless of the type of capacitor), Simple parallel plate: .png Parallel plate with dielectric material in the gap: ]3 Supercapacitor: How is the ...
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### Calculating the self capacitance of a rectangular electrode with a dielectric on one side

I am trying to derive an expression for the capacitance of a rectangular electrode with a dielectric material of thickness $t$ and relative permittivity $\epsilon_r$ in contact with one side, sized ...
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### Effects generated from a supercapacitor placed in a time varying external magnetic field?

The diagram above, showcases the simple outlook of a supercapacitor's interior and combining it with a full circuit loop. If an exterior magnetic field is introduced in all the operating states of a ...
0answers
27 views

### Metal Oxide Semiconductor (MOS) Capacitor strong inversion

Why the electron bands in the Body of the MOS capacitor do not bend much futher after the threshold voltage is applied? What stops them from doing it? For reference Modern Semiconductor Devices for IC ...
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### RC circuit discharge while being connected to a battery?

I am facing a conceptual problem in analyzing the following situation which was part of a physics exam: A series RC circuit with $R = 200k \Omega$ and $C = 10 \mu F$ is connected to a 5V battery and ...
1answer
54 views

### Resolve The Envelope Detector Circuit

I was working on a little project and I was wondering if the envelope detector circuit could be resolved analytically. Let me explain. The circuit is the one shown above, I know the values of $C$, $R$...
2answers
1k views

### Influence of an external electric field on an uncharged capacitor

Influence of an external electric field on an uncharged capacitor. Fig A shows an uncharged capacitor with no external electrical field. There is no net charge on each of the plates. Since the ...
0answers
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### Is the permittivity of a dielectric medium measured by application of radio frequency of 1 KHz and a resonant circuit of 1KHz are same?

I am working on a procedure in which I assess the dielectric constant of a medium by subjecting the dielectric medium to electromagnetic radiation of certain frequency (or the medium is subjected to a ...
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821 views

### Capacitance of spherical capacitor when inner sphere is earthed

Consider the following derivation: (Source: http://www.ncert.nic.in/html/learning_basket/electricity/electricity/electrostatics/inner_sphere.htm) If a charge of $+Q$ coulombs is given to the outer ...
2answers
65 views

### Capacitors in Series, which uses the most voltage?

AP Physics teacher here, preparing to teach my students about capacitors. We have some basic breadboards, capacitors, battery packs, and DC power supplies. My plan was to have them put three different ...
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### What size aluminum foil capacitor would power an LED?

Inspired by this video where a $9 \mu F$ capacitor is made from aluminum foil, if I had students put this together in a classroom, one question I would have is what would it take to have this power an ...
2answers
566 views

### Current in discharging capacitor through fixed resistor?

In the textbook I'm using for physics it says that the charge left on the plates of a capacitor after time $t$, that is discharging through a fixed resistor, is $Q=Q_0e^{-t/\tau}$ where $\tau=RC$ is ...
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### What's an intuitive understanding of diffusion capacitance?

Diffusion capacitance often comes up in transistor design. It is one of the two main capacitances you see, the other being the depletion layer capacitance. The depletion layer capacitance (per unit ...
2answers
825 views

### Charged dielectric/conductor in capacitor

It is a standard problem to consider a dielectric or a conductor between the parallel plates of a capacitor. But what happens to capacity, voltage, charge, inserting between the plates of an ideal ...
0answers
209 views

### How is derived the relation between capacitances when a $Y-\Delta$ transformation is applied in a capacitors network?

A $Y-\Delta$ transformation can be applied to circuits in order to make an equivalent circuit (but simpler to put in terms of series/parallel devices). Wikipedia and other books show how to deduce the ...
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1k views

### What is a boundary condition for capacitors/dielectrics?

I am extremely confused about what boundary conditions are. One minute ago I was solving easy capacitor questions and the next minute I am being asked boundary condition questions and there is no such ...
1answer
1k views

### Cylindrical capacitor with 2 dielectrics

I want to calculate $\vec{E}$ and $\vec{H}$ inside this capacitor: So this would be a cylindrical capacitor but with two different dielectrics in it (they both occupy the same amount of space, excuse ...
1answer
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### If iI have a capacitor connected to a battery can the negative charge be sent to an insulated object

If I have a capacitor permanently connected to a battery, that is lets say setting in a plastic bowl, and then run a wire from the negative of the battery to a non grounded object, say a metal can ...