A circuit contains a D-cell battery, a switch, a 60 resistor, and four 16.5 mF c

Question

A circuit contains a D-cell battery, a switch, a 60 resistor, and four 16.5 mF capacitors. The capacitors are connected in parallel, and the parallel group of capacitors is connected in series with the switch, the resistor and the battery. Note that the capacitance units are milli Farad, not micro F. (a) What is the equivalent capacitance of the circuit? Check that you used the formula for adding CAPACITORS in parallel, and double check your units. and (b) What is the RC time constant? Submit Answer Incorrect. Tries 3/15 Previous Tries (c) How long before the current decreases to 48% of the initial value once the switch is closed? Submit Answer Tries 0/15

Explanation / Answer

(A) for parallel capacitor,

Ceq = C1 + C2 + C3 + C4

= (4 x 16.5)

= 66 mF  

(B) T = R C = (60)(66 x 10^-3)

= 3.96 sec  

(C) I = I0 [ e^(-t/RC)]

0.48 I0 = I0 e^(-t / 3.96)

-t / 3.96 = ln(0.48)

t = 2.91 sec

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