Calculate Time for Charging/Discharging Capacitor w/16V Battery

[IKonquer]

A 16 V battery, a resistor with R = 106Ω and a 6-μF capacitor are connected in
series with a switch. Find the time taken for the capacitor;
a) To charge to a voltage value of 12V
b) Time to discharge to a value to 7V, after it has fully charged to 16V

a) $$V_c = V_o \cdot \left(1 - e^\frac{-t}{RC} \right)$$

Would $$V_o$$ be 16 and $$V_c$$ be 12?

b) $$V_d = V_o \cdot e^\frac{-t}{RC}$$

Would $$V_o$$ be 16 and $$V_d$$ be 7?

 

[Apphysicist]

Yep. It might help to visualize the exponential graphs:

Charging:

http://www.wolframalpha.com/input/?i=16*%281-e^%28-x%2F0.000636%29%29+from+x%3D0+to+x%3D.00318

Discharging:

http://www.wolframalpha.com/input/?i=16*%28e^%28-x%2F0.000636%29%29+from+x%3D0+to+x%3D.00318

V_0 is always your y-intercept.