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e 10-11r capacitor? V,- Problem 3: Charge flow through switch The capacitors in

ID: 1770390 • Letter: E

Question

e 10-11r capacitor? V,- Problem 3: Charge flow through switch The capacitors in this diagram are initially uncharged and are connected with applied potential difference is Va 210. , 25V 3.00 F 6.00 F a. (l 12. 6.00 F 3.00 F (a) What is the potential difference Ved? (b) What is the energy stored in each capacitor? (c) What is the potential difference across each capacitor after the switch S close (d) What is the energy stored in each capacitor after the switch S closed? Ve (e) How much charge flowed through the switch when it was closed? Vae =?

Explanation / Answer

c) Once switch is closed the equivalent circuit would be

C13 = C1 +C3

        = 9uF

C24 = C2+C4

        =9uF

CT = C13*C24 / (C13 +C24)

     = 9*9 / 18 = 4.5uF

Voltage across C13 = CT /C13 *Vab = 4.5/9 *210 = 105V

Voltage across C24 = CT /C24 *Vab = 4.5/9 *210 = 105V

V1 =V3 = V13 = 105V (parallel)

V2 =V4 =V24 = 105V (parallel)

d) Energy stored E = 1/2CV2

E1 = 1/2*3*(105)2 = 0.01653J

E2 = 1/2*3*(105)2 = 0.033J

E3 = 1/2*3*(105)2 = 0.033J

E4 = 1/2*3*(105)2= 0.01653J

e) Charge trrough switch = difference of charge between C1 and C3

Q1 = V1C1 = 105*3 = 315uC

Q3 = V3C3 = 105*6 = 630uC

Qswitch = Q3-Q1 = 315uC = 3.15*10-6C