(a) What is the charge on the capacitor? Answer = _______________ C (b) The swit

Question

(a) What is the charge on the capacitor?
Answer = _______________ C (b) The switch is opened at t = 0 s. At what time hasthe charge on the capacitor decreased to 10% of its initialvalue?
Answer = ________________ ms Consider the circuit in the figurebelow, in which V = 80 V, R = 30 Ohm, and theswitch has been closed for a very long time. Opens at t=0 s (a) What is the charge on the capacitor? Answer = _______________ MuC (b) The switch is opened at t = 0 s. At what time hasthe charge on the capacitor decreased to 10% of its initialvalue? Answer = ________________ ms

Explanation / Answer

. 01.   R = 30 02.   After a long time, the capacitor willappear as an open circuit and its voltage will equal the voltagedrop across R. 03.   VR = (80volts)*[(30)/(30+60)] = 26.667 volts 04.   Q = C*V = (2.0E-6 Farads)*(26.667 volts)= 53.33E-6 Coulombs= 53.33Coulombs . 05.   = time constant = RTotal*C =(30+10)*(2.0E-6 Farads) = 80.0E-6 seconds 06.   VC =(VC0)*exp[(-t)/()] 07.   (VC)/(VC0) =0.10      ;   Given inproblem statement 08.   0.10 = exp[(-t)/(80.0E-6seconds)]      ;   solvefor t 09.   ln(0.10) = (-t)/(80.0E-6 seconds) 10.   t = (-80.0E-6 seconds)*ln(0.10) = 184.207E-6seconds = 0.1842milliseconds .

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