A 100 μ F capacitor and a 3.6 k Ω resistor are connected in series. How long will it take for the capacitor to change its charge completely?
A) 1.8 s
B) 2.3 s
C) 3.8 s
D) 4.3 s

Question

Quizplus · Accepted Answer

The time it takes for a capacitor to charge or discharge through a resistor is given by the time constant τ = RC, where R is the resistance in ohms (Ω) and C is the capacitance in farads (F). For a 100 μF capacitor and a 3.6 kΩ resistor, τ = (3.6 kΩ)(100 μF) = (3.6 × 10^3 Ω)(100 × 10^-6 F) = 0.36 seconds. However, to completely change its charge (i.e., to charge or discharge fully), it is commonly considered to take about 5 time constants (5τ). Thus, the total time is 5 × 0.36 s = 1.8 s.

A 100 μ F Capacitor and a 3