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CAPACITOR

santosh_bangaru

May 22, 2013
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hi,

any one please explain me why capacitor will not allow sudden change in current.
and why inductor does not allow sudden change in current

thanks
santosh
 

duke37

Jan 9, 2011
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A capacitor will not allow a sudden change in VOLTAGE.

Capacitors and inductors store energy so in order to increase the voltage on a capacitor you need to provide energy. In order to increase the current through an inductor you need to provide energy.

This cannot be done instantly so changes are slowed.

EnergyCapacitor = C * V * V / 2
EnergyInductor = L * I * I /2
 

komalbarun

Nov 25, 2011
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If i charge a capacitor with a 0.1A current, and then i connect it to a LED as a battery* will the current leaving the capacitor be 0.1A, assuming that no resistors are in the circuit?

I think yes because of the charge time and discharge time being 5CR , am I right?
 

shrtrnd

Jan 15, 2010
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'ELI the ICE man', is the way they taught us in school.
E (Voltage) before I (Amperage) in an L (Inductor)
I (Amperage) before E (Voltage) in a C (Capacitor).
 

BobK

Jan 5, 2010
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No, it will provide (for a short time) whatever current the circuit it is connected to will take. This is why capacitors charged to high voltages are so deadly.

If you bring an inductor up to 100mA, then disconnedt the current soruce, it will try to continue that current of 100mA creating as high a voltage as it needs to do so.

Bob
 

komalbarun

Nov 25, 2011
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No, it will provide (for a short time) whatever current the circuit it is connected to will take. This is why capacitors charged to high voltages are so deadly.

If you bring an inductor up to 100mA, then disconnedt the current soruce, it will try to continue that current of 100mA creating as high a voltage as it needs to do so.

Bob
so after I charged the capacitor with a 100mA current, then I connect it to a circuit requiring a 200mA current, 200mA will flow out of the capacitor for a short time?
Would this be why capacitors create a spark when its leads are short circuited?
 

BobK

Jan 5, 2010
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Yep. Capacitors have very low resistance, compared to a battery, so a large current will flow when you short them.

Bob
 

santosh_bangaru

May 22, 2013
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A capacitor will not allow a sudden change in VOLTAGE.

Capacitors and inductors store energy so in order to increase the voltage on a capacitor you need to provide energy. In order to increase the current through an inductor you need to provide energy.

This cannot be done instantly so changes are slowed.

EnergyCapacitor = C * V * V / 2
EnergyInductor = L * I * I /2

yes i have done a mistake.
YES capacitor will not allow sudden change in VOLTAGE.
can you please explain me the detailed reason for the capacitor will not allow the change in vooltage.
if it allows what happens. and the same for inductor also
 

santosh_bangaru

May 22, 2013
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No, it will provide (for a short time) whatever current the circuit it is connected to will take. This is why capacitors charged to high voltages are so deadly.

If you bring an inductor up to 100mA, then disconnedt the current soruce, it will try to continue that current of 100mA creating as high a voltage as it needs to do so.

Bob

yes thats good i think,
inductor does not allow sudden change in the current so it will allow to pass the same current even though the source is not present.
 
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