RC Circuit?

Question

R = 200 Ω, C = 2.0 μF. Initially the capacitor is charged up to 100 Volts. Then the switch is closed, and the capacitor is discharged. Select True or False for the following statements.

The time constant τ of the circuit is 4.00E-4 s.? true or false
If the resistance R is doubled, then the capacitor will be discharged twice as slow. true or false?
After one time constant the voltage across the resistor is 36.8 V. true or false

Answer 1

If you're doing this in class you need to do some important but should-be-easy catching up. These are the most basic questions about exponential decay. Anyway,
(1) time constant = RC, R in Ω, C in F. You can answer from that.
(2) doubling R doubles the time constant. This doubles the time needed to do the same amount of discharging, so it's twice as slow.
(3) After 1 TC the voltage is 1/e * its initial value. You decide if T or F.