capacitor and inductor

Thread Starter

bhuvanesh

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

crutschow

Joined Mar 14, 2008
34,282
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.
 

Thread Starter

bhuvanesh

Joined Aug 10, 2013
268
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
 

crutschow

Joined Mar 14, 2008
34,282
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
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.
 
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