# capacitor and inductor

Discussion in 'General Electronics Chat' started by bhuvanesh, Apr 20, 2014.

1. ### bhuvanesh Thread Starter Member

Aug 10, 2013
268
2
voltage and why voltage cannot change instantaneously in capacitor but current but why current cannot change instantaneously in inductor.Thank you in advacne

2. ### crutschow Expert

Mar 14, 2008
13,501
3,375
Just look at the equations:

The voltage on a capacitor is V = Q/C where Q is the capacitor charge. To change the voltage requires a change in its charge (ΔQ = I*t) where I is current and t is time. Thus to change the voltage instantaneously (t = 0) requires an infinite current.

To change the inductor current requires a voltage across it (ΔI/t = V/L or ΔI = V/L * t). Thus to change the current instantaneously (t = 0) requires an infinite voltage.

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3. ### bhuvanesh Thread Starter Member

Aug 10, 2013
268
2
okay then how the current changes instantaneously in capacitor(i=vc/t).we dont have infinite current to make change the current instantaneously.but it actually changing instantaneously.i know i misunderstood something but i dont know what.help me

4. ### crutschow Expert

Mar 14, 2008
13,501
3,375
The current can change instantly (assuming no parasitic inductance) but not the voltage, since the current has to flow for some finite time to change the voltage on a capacitor.