Xc - Capacitors in AC Series RC Circuit

in electricity •  9 months ago


I published this video to help students awhile back. It is geared for people that have been introduced to electricity and have a foundation in Ohm's law. It is also best if you understand the fundamental capacitor as used in a DC (direct current) application. There is a link at the bottom of this post to capacitor fundamentals.

This video shows the effect of changing frequency in an AC (alternating current) series circuit with a resistor and a capacitor. Calculations are explained and results are measured on the scope.


As mentioned in the video, a capacitor is ideally an AC short. I use the term ideally, as when sized properly a capacitor can block DC (direct current) and pass AC (alternating current). The reality is depending on the frequency and the capacitance, AC can charge and discharge through a capacitor. The video helps explain this property, and demonstrates phase shift. In a capacitive circuit the current leads the voltage.

The video covers Z (Impedance), XC (Capacitive Reactance), along with voltage and current in a series RC (resistor-capacitor) circuit. Topics involving phase angle and power factor are not covered, but the video is a good intro into AC power.

Another interesting point mentioned in the video is electrical current does not flow through the dielectric, but electrons move through the circuit from one plate to another. Keep in mind that a capacitor is two conductors (plates) separated by an insulator (dielectric).

Once you comprehend the fundamentals of capacitance you will be amazed with how many practical uses this component offers.

There are plenty of resources on capacitors, particularity basics and DC. I made this video in an effort to help understand capacitors in AC circuits.

If you need more understanding of the basics, I recommend the link below

Sparkfun has done a great job explaining capacitors - https://learn.sparkfun.com/tutorials/capacitors

What do you think? Does my video help? Do you have any questions about capacitors? What topics in electronics and electricity need more attention?

Thanks for watching my video! --3D

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