Consider an RC circuit with a capacitance of 150 μF and a resistance of 1 MΩ connected to a 200-V power source for a long time, disconnected, and shorted. How long should one wait before the voltage across the capacitor drops to below 50 V?
a)208 s
b)314 s
c)52 s
d)104 s
e)176 s

Question

Consider an RC circuit with a capacitance of 150 μF and a resistance of 1 MΩ connected to a 200-V power source for a long time, disconnected, and shorted. How long should one wait before the voltage across the capacitor drops to below 50 V?
	 a)208 s
	 b)314 s
	 c)52 s
	 d)104 s
	 e)176 s

anonymous · Answer

a)208s

mos1635 · Answer

Vc=Vo*e^(-t/RC)
set Vc=50
Vo=200
R=10^6
C=150*10^(-6)
and solve.......