Answer to Question #156656 in Electric Circuits for sheena sheen

Question

What capacitance when connected in series with a 500Ω resistor will limit the current

drawn from a 48-mV 465-kHz source to 20μA?

Answer 1

Answer

For RC circuit resistance is given by

$Z=\frac{V}{I}=\sqrt{R^2+X_c^2}$

$X_c=\frac{1}{2\pi fC}$ -------eq1

So using above equation capacitance can be written as

$X_c=\sqrt{\frac{V^2}{I^2}-R^2}$

$X_c=551\times10^4 ohm$ -------eq2

Using equation 1 and 2

Capacitance

$C=\frac{1}{2\times3.14\times465\times10^3\times23.47\times10^2}$

C=0.15nF