But there's a HUGE HOLE in your electronic education.
Because it doesn't TELL you what you think it does.
What you want is a Wattmeter. And a 'scope.
Yes the utility company is charging per watt. But the amount of watts are directly tied to how many amps. So if I have one system pulling 10 amps, and one pulling 20 amps . . . well I don't need a degree to know which will be more watts do I ?
And utility cost is only part of the question.
We buy wire, breakers, and fuses based on amps. If our home shop is limited on supply voltage/amps. . . well knowing the amps will answer some other questions.