In the RC circuit pictured below, he switch has been closed for a long time, and
ID: 2276362 • Letter: I
Question
In the RC circuit pictured below, he switch has been closed for a long time, and the capacitor in the circuit is fully charged. When switch S is opened, the battery is not part of the circuit anymore and the capacitor starts discharging. The capacitance is C = 0.2 ?F, the resistance is R = 5 ?, and the voltage provided by the battery is ? = 12 V.
A. 0.4 A
B. 1.4 A
C. 2.4 A
D. 3.4 A In the RC circuit pictured below, he switch has been closed for a long time, and the capacitor in the circuit is fully charged. When switch S is opened, the battery is not part of the circuit anymore and the capacitor starts discharging. The capacitance is C = 0.2 ?F, the resistance is R = 5 ?, and the voltage provided by the battery is ? = 12 V.
Explanation / Answer
a)
Io =E/R =12/5
Io =2.4 A
b)
Time constant
T=RC =5*0.2*10^-6
T=10^-6 F
Given
I =Io/2
I=Io*e^(-t/T)
Io/2 =Io*e^(-t/10^-6)
Ln(0.5)=-t/10^-6
t=0.7*10^-6 s