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CAPACITOR

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

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  1. santosh_bangaru

    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

    duke37

    5,364
    771
    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

    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

    shrtrnd

    3,821
    519
    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

    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

    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

    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

    santosh_bangaru

    3
    0
    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

    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.
     
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