Discussion Forum

A series R-C combination is connected to an AC voltage of angular frequency $\omega$= 500 rad/s. If the impedance of the R-C circuit is $R\sqrt{1.25}$, the time constant (in millisecond) of the circuit is

Answer:

Explanation:

$Z=\sqrt{R^{2}+X_{C}^{2}}=R\sqrt{1.25}$

 $\therefore$  $R^{2}+X_{C}^{2}=1.25R^{2}$

 or $X_{C}=\frac{R}{2}$

 or   $ \frac{ 1}{ \omega  C}=\frac{R}{2}$

 $\therefore$  Time constant  = CR= $\frac{2}{\omega}$

       $\frac{2}{500} s=4ms$

 $\therefore$  Answer is 4