Academic Integrity: tutoring, explanations, and feedback — we don’t complete graded work or submit on a student’s behalf.

home / study / questions and answers / science / physics / a circuit is construc

ID: 1594044 • Letter: H

Question

home / study / questions and answers / science / physics / a circuit is constructed with four resistors, one ...

Your question has been answered! Rate it below.

Let us know if you got a helpful answer.

Question

A circuit is constructed with four resistors, one capacitor, one battery and a switch as shown. The values for the resistors are: R1 = R2 = 38 , R3 = 61 and R4 = 150 . The capacitance is C = 48 F and the battery voltage is V = 12 V. The positive terminal of the battery is indicated with a + sign.

What is Q(), the charge on the capacitor after the switch has been closed for a very long time?

After the switch has been closed for a very long time, it is then opened. What is Q(topen), the charge on the capacitor at a time topen = 680 s after the switch was opened?

What is IC,max(closed), the current that flows through the capacitor whose magnitude is maximum during the time when the switch is closed? A positive value for the current is defined to be in the direction of the arrow shown.

Explanation / Answer

Q(), the charge on the capacitor after the switch has been closed for a very long time

Voltage across capacitor = 12/(38 + 61 +150) * 61

                                         = 2.94 V

=>   Q(), the charge on the capacitor = 48 *10-6 * 2.94

                                                               = 1.41 *10-4 C

the charge on the capacitor at a time topen = 680 s = 1.41 *10-4 * e(-0.1431)

                                                                                                               = 1.22 *10-4 C

IC,max(closed), the current that flows through the capacitor whose magnitude is maximum during the time when the switch is closed

=>   IC,max(closed) = 0.05676 *61 /38

                               = 0.0911 A