Your engineering firm has built the RC circuit shown above. The current is measu

Question

Your engineering firm has built the RC circuit shown above. The current is measured for the time t after the switch is closed at t = 0 and the best-fit curve is represented by the equation l(t) = 5.20 e^-t/10, where l is in milliamperes and t is in seconds. Determine the value of the charging voltage V_0 predicted by the equation Determine the value of the capacitance C predicted by the equation. The charging voltage is measured in the laboratory and found to be greater than predicted in part (a).

Explanation / Answer

for charging RC circuit, current in the circuit is given theoretically as

i(t)=(V0/R)*exp(-t/(R*C)) A

cpmparing with the result obtained experimentally,

V0/R=5.2 mA

==>V0=50*10^3 ohms * 5.2*10^(-30 A

=260 volts

part v:

comparing with the equation of i(t) obtained experimentally,

R*C=10 seconds

==>C=10/(50*10^3)=200 uF(=200*10^(-6) F)

part c:

part 1

ideal capacitor is very hard to obtain.

every capacitor has some leakage resistance which increase total resistance in the circuit

hence to obtain same current, voltage will have to be higher than what is obtained with ideal capacitor.

part 2:

as capacitance=time constant/resistance

if resistance is increased due to the non-ideal capacitor, then capacitance will decrease.

part d:

to decrease charging time, you have to decrease the time constant

as time constant=R*C

then either increase resistance or capacitance

to increase resistance conenct the resistor in series

part ii. to increase capacitance, connect the cpaacitor in parallel.

Related Questions

Navigate

• Browse (All)
• Browse Y
• Subjects

---

---

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