I'll give it a shot, but you should study the Quantec illustrations. When Quantec sets off electrical charges (by computer) along the central line of the land they are investigating, on each side there are two sensor lines that pick up the induced polarization. The induced current is sent into the ground every 50 meters, and the time and amount of current the pickup electrodes (say 50 meters on each side of the central ones) measure is stored in their computers.

Metals such as copper, gold, sodium are good conductors, so if you sent in a huge voltage with enough amperage at point "A" and your brother (who always teases you) is ten feet away with his wet finger in the wet soil will yelp when he gets a shock. Depending on the amount of gold and/or sulfides in the host rock, the conductivity, resistance and chargeability can be calculated.

The induced voltage is not quite the same as your house alternating current; those waves are smooth like the waves in a quiet ocean, half are above the middle and half below, so the current is alternating between a positive charge and a negative charge. Quantec uses a square wave generator, so the wave is square or rectangular like a loaf of bread, and is sitting on the middle line and the current is only positive, or a direct current.

Now if you measure chargeability, why do you have the result in a tiny part of a circle? The answer is that because is that part of the induced voltage is building up in the ore body, just like the flash capacitor in your camera. This causes the latter part of the square wave to be shaven off the top of the riight hand side of our loaf of bread, if you will. That portion of the "defect" is the amount of current that has been charged into the ore body. If you look at the Quantec diagrams, they show that in small increments in time the slope of the points of measurement the pickup electrodes are demonstrating, the successive slopes are changing in time sequence. This small change in the slopes of one measurement and the next are measured in radians, similar to moving the hand on a clock a small amount, you could measure the changes you have made in radians.

So that's my version of why changes in chargeability are measured in tiny degrees of a circle.

The whole thing tired me out!