physics

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how a bleeder resistor (R = 260 k) is used to discharge a capacitor (C = 85.0 µF) after an electronic device is shut off, allowing a person to work on the electronics with less risk of shock.

Figure 20.47
(a) What is the time constant?


(b) How long will it take to reduce the voltage on the capacitor to 0.350% of its full value once discharge begins?


(c) If the capacitor is charged to a voltage V0 through a 125 resistance, calculate the time it takes to rise to 0.865V0 (this is about two time constants).


I got part a and b... but i don't know how to get part c! a is 22.1s, part b is 125 s....

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