# CAPACITOR

Discussion in 'General Electronics Discussion' started by santosh_bangaru, May 22, 2013.

1. ### santosh_bangaru

3
0
May 22, 2013
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

2. ### duke37

5,364
772
Jan 9, 2011
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

3. ### komalbarun

67
0
Nov 25, 2011
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?

4. ### shrtrnd

3,827
521
Jan 15, 2010
'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).

5. ### BobK

7,682
1,688
Jan 5, 2010
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

6. ### komalbarun

67
0
Nov 25, 2011
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?

7. ### BobK

7,682
1,688
Jan 5, 2010
Yep. Capacitors have very low resistance, compared to a battery, so a large current will flow when you short them.

Bob

8. ### santosh_bangaru

3
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May 22, 2013
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

9. ### santosh_bangaru

3
0
May 22, 2013
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.