How to Convert Capacitance from the Time Domain to the Frequency Domain

To convert Capacitance from the time domain to the frequency domain, we use the formula:

Capacitance in the Frequency Domain= 1/(jwc)

where

w= the radians per seconds (rad/s) of the power source
l= the Capacitance of the capacitor

Example

If a power source of 20cos4t V is powering a capacitor of 0.1F, the capacitance is

Capacitance in the frequency domain = 1/(jwc)
=2/(j(4)(0.1))
=-j2.5