Measuring cup, graduated cylinder, anything that has volumetric markings to tell you how much liquid you have. Or if the liquid has a known density, you can weigh it and determine its volume from mass/density. (You just have to make sure your units are all the same scale--if you weigh in lbs. and have density in grams/cubic centimeters, you have to convert lbs. to grams before using the density equation.
I know the basics of how to find these values from a graph, but not sure how to prove that average voltage of half-wave rectifier is peak/pi and rms is peak/2. Same for full-wave rectifier where average is 2peak/pi.
In building a rectifier circuit, one must choose a diode that can safely withstand the current the circuit will have to provide, and also the reverse bias voltage that will be applied to it. Diodes are rated for maximum average forward current, which, since the diode conducts only half the time (positive-going half-cycles only), is roughly 1/2(V av /R L), where V av is the average voltage and R L is the load resistance.