Well that's easier that if you wanted to know the voltage and the current separately.Well i need the current to calculate the power in KW.
But for my own vision, the Amplifier will give voltage around 1v to the Arduino linear to it's measured current right. And i have to put that to RMS to know the exact current right?
All you have to do is sample, (You will need at least 16 samples per cycle) multiply the instantaneous voltage by the instantaneous current and average the result (a 1st order IIR filter will do the job). No need for any squares or square roots.