Question

There is circuit with one resistor, one capacitor, one switch and a dc voltage source
resistor = 200Ω
dc voltage = 10v
Capacitor = 10 uf = 0.00001f

can someone help me on question 2 and 3

1. what is the RC time constant of the circuit?
answer: (200Ω)(0.00001f)=0.002s

2. What is the time from the instant that the switch closes until the capacitor fully charges? Assume that the capacitor is fully discharged prior to the switch closing?

3. What is the current in the circuit the instant after the switch closes? Assume that the capacitor is fully discharged prior to the switch closing

Answer 1

2 --- forever in theory e^-t/RC never actually reaches zero
3 --- at first all the electrons try to go to the empty go to the capacitor but the voltage on the capacitor is zero (no charge yet) so the 10 volts is across the resistor
i = V/R = 10 volts / 200 ohms at the start

Answer 2

2 usually, in practice, many consider 5 time constants will fully charge from zero in an RC circuit.

Answer 3

@Bobpursley, do you mean t=5*rc?

Answer 4

Yes, what bobpursley said means t=5*rc, so anonymous you are correct.