The diagram below depicts an RC -circuit where C 1 = 6.55 ?F, C 2 = 2.45 ?F, R 1
ID: 1362615 • Letter: T
Question
The diagram below depicts an RC-circuit where C1 = 6.55 ?F, C2 = 2.45 ?F, R1 = 22.5 ?, R2 = 23.5 ?, and ?1 = 6.00 Volts.
1. What is the final amount of charge stored in C2?
(in C)
2. What is the amount of charge stored in C1 after the switch S has been closed for t = 5.00E-6 seconds?
(in C)
3. What is the initial current through the circuit immediately after the switch S is closed?
(in A)
4. What is the current through the circuit after the switch S has been closed for t = 5.00E-6 seconds?
(in A)
Explanation / Answer
C1 = 6.55 F, C2 = 2.45 F, R1 = 22.5 , R2 = 23.5 , and 1 = 6.00 Volts.
R1 and R2 are in parallel
1/R = 1/R1 + 1/R2
1/R = 1/22.5 + 1/23.5
1/R = 0.044 + 0.042 = 0.086
R = 11.62 ohms
and C1 and C2 are in series
1/C = 1/C1 + 1/C2
1/C = 1/6.55 + 1/2.45
1/C = 0.15 + 0.408 = 0.558
C = 1.79 F
1)
the final amount of charge stored in C2
Q = C V
Q = 1.79 X 10-6 X 6
Q = 10.74 X 10-6 C
Q = 1.074 X 10-5 C
option : F
2)
Q = CV( 1 - exp(-t/RC))
Q = 2.45 X 10-6 X 6( 1 - exp(-5X10-6/11.62 X 2.45 X 10-6 ) )
Q = 2.45 X 10-6 X 6( 1 - 0.84 )
Q = 14.7 X 10-6 X 0.16
Q = 2.352 X 10-6 C
option : G
3)
i = V X exp(-t/RC)/ R
i = 6 X exp(-1) / 11.62
I = 6 X 0.36 / 11.62
i = 1.18×10-1 A
Option : C
4)
i = V X exp(-t/RC)/ R
i = 6 X exp(-5 X 10-6 / 11.62 X 1.79 X 10-6)/ 11.62
i = 6 X 0.78 / 11.62
i = 0.40
i = 4.0 X 10-1
option : B