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Questions tagged [capacitance]

The ability of an object to store electric charge.

Often the concept capacitance is applied to two separated conductors, as a potential difference between them is applied. The SI unit for capacitance C is farad (F).

$${C={Q}/{V}}$$

Where Q is the charge in the object and V is voltage across the two conductors.

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Capacitors in series: Why is the equivalent charge the same as the individual charges

Consider two parallel-plate capacitors $C_1, C_2$ in series. For the "equivalent" circuit, clearly $$ Q_{equiv} = C_{equiv}V$$ should hold, where V is the total voltage drop between input and output. It is also obvious that $$ Q_1 = Q_2 $$ where…
Timtam
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How feasible is it to use the dielectric constant of a liquid to determine specific gravity?

I homebrew my own beer and I'm looking for way to cheaply monitor the specific gravity of my brew during the fermentation process. I came across this thread that seems to indicate capacitance may be used to determine specific gravity. Is there a…
Eric Ryan
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What are some reasons to connect capacitors in series?

When you join capacitors in series, the equivalent capacitance decreases. What are some reasons to connect capacitors in series?
user31058
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Energy changes due increasing plate separation of unconnected charged capacitor

If a capacitor is charged by a source with constant voltage, $V$, the energy, $W$, stored by a capacitor of capacitance $C$ is given by: $$ W = \frac{1}{2} QV = \frac{1}{2} V^{2}C = \frac{Q^{2}}{2C} $$ where $Q$ is the charge stored on the…
Jon Hurst
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Principle of mutual capacitive touch screen

I'm curious about how the mutual capacitive touch screen works, so I did some research on internet and found an excellent explanation: youtube video. According to the video, this is how the mutual capacitive touch screen works (if there is any…
ice_lin
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Capacitors in series?

Capacitors in series have identical charges. We can explain how the capacitors end up with identical charge by following a chain reaction of events, in which the charging of each capacitor causes the charging of the next capacitor. We start with…
dfg
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Why exactly do capacitors charge and discharge exponentially?

Hi this is my first time posting so please feel free to correct me on any formatting errors I may make. I understand that as a capacitor charges, the amount of electrons that are deposited on one plate increases, thereby the overall voltage across…
Kouzan
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Does connecting a capacitor in parallel with a wire "short" it out?

I have a question about capacitors. In the circuit below, capacitor C2 is in parallel with a wire. When a resistor is connected in parallel to a wire, the potential across it equals zero so no current goes through it. My questions are does the…
christina
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Does the energy inside a capacitor has a variable dependency of the capacity?

While studying energy inside capacitors, I came up with something: If we can calculate the energy inside it as: $$U=\frac{1}{2}QV=\frac{1}{2}CV^2=\frac{1}{2}\frac{Q^2}{C}$$ Then, why in some cases it appears that the energy depends directly or…
Luis_V
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Parallel Plate Capacitors

I was wondering what would happen to capacitance if the plates are not parallel (above/below each other) or if the plates are not the same size. Thanks.
321
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Why do some capacitors leak and other capacitors hardly leak at all?

I just found out that electrolytic capacitors hardly leak whereas non-electrolytic capacitors leak and at times, leak a lot. Questions: (a) what causes capacitors to leak? (b) why do electrolytic capacitors hardly leak when wired correctly whereas…
Jesus
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Procedure to find capacitance matrix for a network of mutual capacitances, where some nodes are left to float

Suppose we have a network of circuit nodes connected to each other via two-terminal mutual capacitances $C_{m,ij}$. Is there a recipe for finding the capacitance matrix for this network, and for eliminating certain nodes that are allowed to…
DanielSank
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Why does electric field lines bulge out at the endings in a parallel plate capacitor?

I am trying to draw out electric field lines for different conducting bodies, and I know that electric lines in case metallic conductors incident and emerge out perpendicularly, considering a parallel plate capacitor's base component is a metallic…
Madhav Satheesh
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Why does touching the microphone cable stop my headphone from humming?

This might sound like a techical problem, but i'm more interested in the physics aspect of it. I have headphones that are connected to my pc with a single cable. I also have a microphone attached to the headset, that is connected to the pc with…
rogerg
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Capacitor and hydraulic analogy

Would anyone kindly explain me the hydraulic analogy for the working of a capacitor w.r.t the article of wikipedia http://en.wikipedia.org/wiki/Capacitor... Help!!
Four Seasons
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