A circuit as shown is constructed with a 100 ohm resistor and a 20 microF capaci

Question

A circuit as shown is constructed with a 100 ohm resistor and a 20 microF capacitor. The capacitor initially has a charge of 360 microC

a) Before the switch is closed, determine the potential difference across the capacitor, the potential difference across the resistor, and the current through the resistor.

b) At the instant the switch is closed, determine the potential difference across the capacitor, the potential difference across the resistor, and the current through the resistor.

c) At a time 2.0 ms after the switch is closed, determine the charge of the capacitor, the potential difference across the capacitor, the potential difference across the resistor, and the current through the resistor.

Explanation / Answer

given

R = 100 ohms
C = 20 micro F
Qo = 360 micro C

a) apply, Qo = C*Vo

==> Vo = Qo/C

= 360/20

= 18 V

b) VC = 18 V

VR = 18 V

I = VR/R

= 18/100

= 0.18 A

c) time constant of teh ckt, T = R*C

= 100*20*10^-6

= 2 ms

at time, t = 2 ms

Q = Qo*e^(-t/T)

= 360*e^(-2/2)

= 132 micro C

VC = Q/C

= 132/20

= 6.6 V

VR = VC

= 6.6 V

I = VR/R

= 6.6/100

= 0.066 A

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.