Time Constant of Circuit - General Physics - Solved Past Paper, Exams of Physics

Download Time Constant of Circuit - General Physics - Solved Past Paper and more Exams Physics in PDF only on Docsity! 2. (25 pts) An RC-circuit is shown below. + 270 µF 33 k 47 k 10 V a) (5 pts) What is the time constant of this circuit? 1 R = 1 33 + 1 47 R = 19.39 kΩ τ = RC = ( 19.39 × 103 ) ( 270 × 10−6 ) = 5.24 s b) (5 pts) If the capacitor is initially uncharged, how much charge is on the capacitor after the circuit has been connected for 2 s? q(t) = V C [ 1 − e− t RC ] = (10) ( 270 × 10−6 ) [ 1 − e− 2 5.24 ] = 857 µC c) (5 pts) What is the potential on the capacitor after 2 s? V = Q C = 857 × 10−6 270 × 10−6 = 3.175 V d) (10 pts) How much current is flowing through each resistor at t = 2 s? V = 10 − 3.175 = 6.825 V Since the resistances are in parallel, this is the same for both. Thus, I33k = 6.825 33000 = 207 µA I47k = 6.825 47000 = 145 µA