Root Mean Square (RMS) Voltage and Current 

A description of effective voltage and current (also known as root mean square or RMS voltage and current). I go through a graphical illustration of why RMS voltage is considered the effective voltage and then derive the relationship between the peak voltage of a sinusoid and the RMS voltage without calculus
electronx.ca : My website with lots of open education resources related to electrical and electronic circuits including textbooks, tutorials and practice problems
www.electronx.... : the specific chapter on the basics of AC circuits.
Intro Song Credit: HB Racer by Rachael Pauls