Question

For the given input voltage waveform $V_{\text{in }}(t)$ the output voltage waveform $V_o(t)$, across the capacitor is correctly depicted by:

• A.
• B.
• C.
• D.

Answer 1

Answer: (A)

$V_0(t)=V_{\text{in }}\left(1-e^{-\frac{1}{RC}}\right)$
at $t=5\mu s$
$V_0(t)=5\left(1-e^{\frac{5\times 10^{-6}}{10^3\times 10\times 10^{-9}}}\right)$
$=5\left(1-e^{-0.5}\right)=2V$
Now $V_{\text{in }}=0$ means discharging
$V_0(t)=2e^{-\frac{t}{RC}}=2e^{-0.5}$
$=1.21V$
Now for next $5\mu s$
$V_0(t)=5-3.79e^{-\frac{1}{RC}}$
after $5\mu s$ again $V_0$
$(t)=2.79$ Volt $\approx 3V$