Anonymous
Anonymous asked in Science & MathematicsPhysics · 10 years ago

in LCR circuit only A.C power is used. why not D.C power. explain

Relevance

There's a big difference between steady state condition analisys an transient condition analisys !!!!

in steady state condition (d.c. power supply and transient just overcome) capacitors are an open circuit, while inductors are a short circuit, so a LCR circuits becomes an R circuit ; that's why just AC power supply makes sense.

If investigation covers the transient conditions , then capacitors and inductors have a role even though supplied in d.c.

A couple of examples will better clarify what i mean:

Let's assume to discharge a capacitor C , charged at 10Vdc, over a resistor R : we want to know how discharge current flows Vs time ; differential equation leads to :

i = V/R*e^-t/RC

Let's assume to apply 10Vdc to an L+ R serie circuit : we want to know how current flows Vs time ; differential equation leads to :

i = V/R*(1-e^-t/(L/R)

• Because a capacitor blocks a DC current. What happens when one tries to apply a DC current to an RC circuit? The current exponentially decays to zero.