Measure square wave output power?

I need to know the most simplest way to measure square wave output power to a coil I am experimenting with.

I am using a function/frequency generator to supply symmetrical square waves at a frequency range of 10 to 50 HZ. These square waves are fed into a large 12 inch coil. How do I go about measuring true current, true voltage, and power used by the coil? My coil is powering other devices.

I hope this U tube link directs you to what I am doing. A video is worth 1,000,00 words. Your help will be most appreciated.

YouTube - DOUBLE SPIN

Thanks tom

Do you have an oscilloscope?

Voltage measurement is obvious. Current can be measured by inserting a small resistance (1 Ohm or less) in series with the coil, and then measuring the voltage across the resistor. It helps if you can put the resistor in the ground lead of the coil, because that way you can observe the current with only a single scope channel. If you have to put the current sampling resistor in the high-side, you will have to use the two-channel differential mode (watch the common-mode range) of the scope to measure the current.