Tuesday 17 May 2016

In the given RC circuit, the current is i(t) = 2cos5000t Amp. The applied voltage in volts is :


(a) 28.28 cos (50001-45°)
(b) 28.28 cos (5000/+ 45°)
(c) 28.28 sin (5000/-45°)
(d) 28.28 sin (5000/+ 45°)

Ans: A

1 comment:

Daleep singh said...

First find the capacitive reactance

Give in current equation omega(w) =5000

XL=1/Cw = 1/5000*20*10^-6 = 10 ohm

Resistance=10ohm capacitive reactance =10ohms

Now find total impedance

Z = √(10)2^+(10)^2 = 14.14
Now:
V=IZ 2cos5000t*14.14 = 28.28cos(5000t-45)

-45 is because the voltage lags in capacitor.