Exam Questions Papers - Engineering

Q1:

VR at t < T, t = ∞

A 500e-40x104t, 0

B 100e-40x103t, 0

C 100e-40x106t, 0

D 100e-40x104t, 0

ANS:D - 100e-40x104t, 0

At t = 0, C1, C2, C3 acts as short. entire voltage will appear cross R. At t increases the voltage across the resistance decrease exponentially. T = RCnet = 10 x 2.5 x 10-6 = 25 μ sec Initial voltage VR = V0e-t/RC at t = 0 = 100 = 100 e-t/25x10-6 V. VR = 100 e-40x104t V. At t = ∞, VR = 0 The charge C0 will be distributed in C1, C2, C3 and no current will flow.