Question

-Given a capacitance of 50 nF, what resistance should your circuit have in order to have a time constant of 100 microseconds?

-From the circuit above, if you charged it to 5 Volts, then allow the circuit to discharge how long does it take to reach 1 V?

-What was the charge when the capacitor had a potential difference of 1 V?

-If when charging the capacitor to 5 V it broke down, what could you do to raise the breakdown voltage?

Answer 1

1) Given: C = 50 nF = 50*10^-9 F

Time constant T = 100 us = 100*10^-6 s

Time constant is given:

T = RC

=> R = T/C

= (100*10^-6)/(50*10^-9)

= 2000 ohms or 2 kilo ohm

2) V = V0 e^-(t/T)

=> 1 = 5 e^-(t/(100*10^-6))

=> t = 161 us

3) Q = CV = 50 nC