The figure below shows how a bleeder resistor is used to discharge a capacitor a
ID: 2036062 • Letter: T
Question
The figure below shows how a bleeder resistor is used to discharge a capacitor after an electronic device is shut off, allowing a person to work on the electronics with less risk of shock. What is the time constant? ElectronicC circuit 185 ?F 240 k? Enviar RespuestaTries 0/5 How long will it take to reduce the voltage on the capacitor to 0.280% of its full value once discharge begins? Enviar RespuestaTries 0/5 If the capacitor is charged to a voltage VO through a 105-? resistance, calculate the time it takes to rise to 0.850Vo (This is about two time constants.)Explanation / Answer
time constant T = RC = 240*10^3*85*10^-6 = 20.4 s
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the voltage across capacitor plates decreases as Vc = V*e^-(t/T)
for Vc = 0.28 V
0.28 V = V*e^-(t/20.4)
0.28 = e^-(t/20.4)
time taken = 26 s
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Time constant T = RC = 105*85*10^-6 = 0.008925 s
the voltage across capacitor plates increases as Vc = Vo*( 1 - e^-(t/T) )
for Vc = 0.85 Vo
0.85 Vo = Vo*( 1 - e^-(t/0.008925) )
0.85 = ( 1 - e^-(t/0.008925) )
time t = 0.01693 s <<<----------ANSWER