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.
You want the current rating of the diode to be utilized. For rectifier applications the current goes from zero to a specified current. The diode is rated for average current with the peak current being very high. The way I find average current is to take the sine wave and break it into 16 equal parts.