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capacitor basics

sir,

I have a dout about capacitor discharge.Can a charged capacitor
discharge by connecting its one terminal and ground without using its
other terminal.
 
B

Bob

Jan 1, 1970
0
sir,

I have a dout about capacitor discharge.Can a charged capacitor
discharge by connecting its one terminal and ground without using its
other terminal.

The only way to reduce the voltage of a so-called charged capacitor is by
providing a conductive path between the two terminals of that capacitor.

Earth, or ground is only conductive to other parts of the earth (and rather
poorly). People sometimes refer to a common point in a circuit as "ground".
A circuit's "common" only has a conductive path to real ground (earth) if
it's connected to ground (earth).

Bob
 
Sir,
If we touch one terminal of the charged capacitor , is current flow
through our body to the ground without any contact with other terminal.
 
R

Robin

Jan 1, 1970
0
Sir,
If we touch one terminal of the charged capacitor , is current flow
through our body to the ground without any contact with other terminal.

Can you pull a cork out of a bottle one-handed?
No you *have* to use the other hand to hold the bottle.

Likewise the capacitor can only push as much current out of one
terminal as it pulls into the other.
 
A

Andrew Holme

Jan 1, 1970
0
Sir,
If we touch one terminal of the charged capacitor , is current flow
through our body to the ground without any contact with other terminal.

In electrostatics, you can discharge a body by providing a conductive
path to earth (or anywhere else); but a capacitor is two charged bodies
(plates), holding equal and opposite charges, with an electric field
between them. If you connect a conductive path to one plate, only a
very small percentage of the stored charge will re-distribute itself.
 
A

Andy Baxter

Jan 1, 1970
0
Robin said:
Can you pull a cork out of a bottle one-handed?

yes - you put the corkscrew in, tie it to a long piece of string, and then
whirl it round very-very-fast... ;)
 
A

Andy Baxter

Jan 1, 1970
0
anilmanual said:
sir,

I have a dout about capacitor discharge.Can a charged capacitor
discharge by connecting its one terminal and ground without using its
other terminal.

Sir,

You now have a scientific hypothesis on your hands. Namely that you can
discharge a capacitor by touching only one of its terminals to the ground.
The thing to do with scientific hypotheses is to test them, so think of a
way to do so and try it yourself.
 
K

Kitchen Man

Jan 1, 1970
0
Sir,
If we touch one terminal of the charged capacitor , is current flow
through our body to the ground without any contact with other terminal.

Sir, "current flow" is a misuse of terms, and circuits are circular.
 
R

Rich Grise

Jan 1, 1970
0
Robin said:


yes - you put the corkscrew in, tie it to a long piece of string, and then
whirl it round very-very-fast... ;)

Yabbut, that doesn't work with electrons. (Or, if you're a college boy,
raised on "conventional current", the holes. ;-P )

Good Luck!
Rich
 
J

Jasen Betts

Jan 1, 1970
0
I have a dout about capacitor discharge.Can a charged capacitor
discharge by connecting its one terminal and ground without using its
other terminal.
sir,

not unless the other terminal is connected to ground (or to something that
connected to ground etc...)

except, some capacitors leak charge but that is a slow discharge process.

Bye.
Jasen
 
J

Jasen Betts

Jan 1, 1970
0
If we touch one terminal of the charged capacitor , is current flow
through our body to the ground without any contact with other terminal.

If nothing is touching the other terminal no current will flow through the
one you touch.

Bye.
Jasen
 
Sir,
What is situation in case of lightning .ie lot of electrons are going
to ground...could u pls tell me the actual process of lightning ....
 
J

John Popelish

Jan 1, 1970
0
Sir,
What is situation in case of lightning .ie lot of electrons are going
to ground...could u pls tell me the actual process of lightning ....
In that case, you and the lightning are inside the capacitor, made up
of the ground as one plate and the cloud as the other plate, with the
air between being the dielectric.
 
B

Bill Bowden

Jan 1, 1970
0
The only way to reduce the voltage of a so-called charged capacitor is by
providing a conductive path between the two terminals of that capacitor.

There is a way to reduce the capacitor voltage without a conductive
path. You can add more dielectric, which will increase the capacity,
and reduce the voltage.

-Bill
 
M

Michael A. Terrell

Jan 1, 1970
0
John said:
In that case, you and the lightning are inside the capacitor, made up
of the ground as one plate and the cloud as the other plate, with the
air between being the dielectric.


You forgot to mention that the capacitor is over its rated voltage
when it arcs over. ;-)
 
J

John Popelish

Jan 1, 1970
0
Michael said:
You forgot to mention that the capacitor is over its rated voltage
when it arcs over. ;-)

Golly! So it is.
 
J

Jasen Betts

Jan 1, 1970
0
There is a way to reduce the capacitor voltage without a conductive
path. You can add more dielectric, which will increase the capacity,
and reduce the voltage.

That'll increase the voltage unless the dielectric is a gas and the plates
aren't moving apart to accomodate the extra dielectric.

to reduce the voltage move the plates closer together.
 
T

Tim Williams

Jan 1, 1970
0
Jasen Betts said:
That'll increase the voltage unless the dielectric is a gas and the
plates aren't moving apart to accomodate the extra dielectric.

Eh? He means increasing the effective area of the plates. Not increasing
thickness.

Tim
 
J

Jamie

Jan 1, 1970
0
Sir,
What is situation in case of lightning .ie lot of electrons are going
to ground...could u pls tell me the actual process of lightning ....
actually, i think it's the other way around but then again, i could be
wrong :)
i think they actually travel from the ground up and when the path
is complete you then get an ionized stream which acts like a short
circuit that gives you that nice little light show ect..
 
R

Robin

Jan 1, 1970
0
Jasen said:
That'll increase the voltage unless the dielectric is a gas and the plates
aren't moving apart to accomodate the extra dielectric.

to reduce the voltage move the plates closer together.

No, as originally stated, the voltage will *decrease* with "more
dielectric".

This is because the dielectric is "stretched" and *that* absorbs energy
hence the voltage must drop a little because energy is conserved. See
Feynman's Lectures on Physics volume 2 chapter 10 section 3.

Also see chapter 9 for fascinating (non technical) description of
lightning.

Cheers
Robin
 
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