1) A series R-C combination is connected to an AC voltage of angular frequency ω= 500 rad/s. If the impedance of the R-C circuit is R√1.25, the time constant (in millisecond) of the circuit is A) 5 B) 3 C) 2 D) 4 Answer: Option DExplanation:Z=√R2+X2C=R√1.25 ∴ R2+X2C=1.25R2 or XC=R2 or 1ωC=R2 ∴ Time constant = CR= 2ω 2500s=4ms ∴ Answer is 4