The same voltage is applied between the plates of two different capacitors. When
ID: 1274060 • Letter: T
Question
The same voltage is applied between the plates of two different capacitors. When used with capacitor A, this voltage causes the capacitor to store 14 ?C of charge and3.7 10-5 J of energy. When used with capacitor B, which has a capacitance of 7.7 ?F, this voltage causes the capacitor to store a charge that has a magnitude of qB. Determine qB. The same voltage is applied between the plates of two different capacitors. When used with capacitor A, this voltage causes the capacitor to store 14 ?C of charge and3.7 10-5 J of energy. When used with capacitor B, which has a capacitance of 7.7 ?F, this voltage causes the capacitor to store a charge that has a magnitude of qB. Determine qB.Explanation / Answer
Q = CV
W = (0.5)CV^2
First capacitor
Q = CV
14*10^-6 = CV
C = (14*10^-6)/V
W = (0.5)CV^2
(3.7*10^-5) = (0.5)(14*10^-6/V)(V^2)
(3.7*10^-5) = (7*10^-6)V
V = (3.7*10^-5) / (7*10^-6) = 5.2857 volts
Cap B
Q = CV
Q = 7.7*10^-6 x 5.2857 = 40.699 uC
qB = 40.7 uC