Question

What percentage of the final voltage is reached on an initially uncharged capacitor C, charged through a resistance R after two time constants?

a) 13.53%
b) 36.79%
c) 50%
d) 86.47%

Answer 1

After two time constants, the voltage on an initially uncharged capacitor charged through a resistance reaches approximately 86.47% of its final value.

Step-by-step explanation:

After two time constants, the voltage on an initially uncharged capacitor charged through a resistance reaches approximately 86.47% of its final value. This can be calculated using the equation V(t) = Vf (1 - e-t/RC) where V(t) is the voltage at time t, Vf is the final voltage, t is the time, R is the resistance, and C is the capacitance.

For example, if the final voltage is 10V and the time constant (RC) is 1s, after two time constants (2s), the voltage would be approximately 8.647V (86.47% of 10V).