Please give me reasons and strategy for each question, THANKS! QUESTION 9** This
ID: 1346964 • Letter: P
Question
Please give me reasons and strategy for each question, THANKS!
QUESTION 9**
This and the next three questions refer to the situation described here.
The values of all circuit elements are given in the figure. The capacitor is initially uncharged. Then, at time t = 0, the switch is closed.
What is the current through the battery immediately after the switch is closed?
(a) I = 0.6 A
(b) I = 0.9 A
(c) I = 1.2 A
QUESTION 10*
After the switch is closed, the current through resistor R1
(a) increases with time.
(b) decreases with time.
(c) remains constant with time.
QUESTION 11**
Find the charge on the capacitor a long time after the switch is closed.
(a) Q = 2.0 C
(b) Q = 3.0 C
(c) Q = 4.0 C
(d) Q = 5.0 C
(e) Q = 6.0 C
QUESTION 12**
A long time after the switch has been closed, it is re-opened. What is the time constant for discharging the capacitor?
(a) 2.4 s
(b) 3.3 s
(c) 6.7 s
(d) 10.0 s
(e) 30.0 s
Explanation / Answer
Q 9
Immediately after closing the switch capacitor is short circuited and R2 is bypassed so only R1 and R3 are there in circuit.their equivalent resistance(R1 and R3 are parallel have same value) = 10/2 =5 ohms
current I = V/R = 6/5 = 1.2A(option C)
Q no 10
after closing switch current through R1 decreases as capacitor and R2 come in series with it and increase resistance of the branch.
Q. 11
After a long time capacitor got fully charged and it behave as open circuit. let potential across its terminal is V = potential across R2. as R1 and R2 are equal so potential across R2 = 3V
now Q = CV
Q = 1*10^-6 x 3
Q = 3x10^-6C = 3 micro C
Q.No. 12
time constant
t = Req x C
Req = R1 and R3 series and then parallel with R2
Req = 20 ||10
Req = 20/3 ohms
t = 20/3micro seconds
t = 6.67micro seconds