Series RC circuit is built with a 15 kΩ resistor and a parallel-plate capacitor with 18-cm-diameter electrodes. A 18 V, 36 kHz source drives a peak current of 0.65 mA through the circuit. Part A What is the spacing between the capacitor plates?

Explanation:

Capacitance

A two parallel-plate capacitor has a capacitance of

where

A = area of the plates =

d = separation of the plates

We need to compute C. We'll use the circuit parameters for that. The reactance of a capacitor is given by

where w is the angular frequency

Solving for C

The reactance can be found knowing the total impedance of the circuit:

Where R is the resistance, . Solving for Xc

The magnitude of the impedance is computed as the ratio of the rms voltage and rms current

The rms current is the peak current Ip divided by , thus

Now collect formulas

Or, equivalently

The capacitance is now

The radius of the plates is

The separation between the plates is

okay i have so many questions. but the big one here is: um wt..f is this mess? ?