In the circuit shown in the following figure, C = 6.00 muF, e = 26.0 V, and the
ID: 1443964 • Letter: I
Question
In the circuit shown in the following figure, C = 6.00 muF, e = 26.0 V, and the emf has negligible resistance. Initially the capacitor is uncharged and the switch S is in position 1. The switch is then moved to position 2, so that the capacitor begins to charge. What will be the charge on the capacitor a long time after the switch is moved to position 2? After the switch has been in position 2 for 4.00 ms, the charge on the capacitor is measured to be 110 |jC. What is the value of the resistance R? How long after the switch is moved to position 2 will the charge on the capacitor be equal to 99.0% of the final value found in part (a)?Explanation / Answer
a) charge on capacitor after long time = 6 * 26
= 156 microC
= 156 * 10-6 C
b) Here, 110 = 156 * (1 - e-4/RC )
=> 0.7051 = (1 - e-4/RC )
=> RC = 3.275 msec
=> R = 545.83 ohm --------------> value of resistance R
c) Here, 0.99 = (1 - e-t/3.275)
=> e-t/3.275 = 0.01
=> t = 15.082 msec
= 0.01508 sec ----------------> time after 99 % of its final value .