electrical current
We're all advised to change the batteries in our smoke detectors once each year. This is truly good and affordable advice, and most of us are happy to comply. If you were to decide on a whim to replace all of the batteries in all of your battery-powered appliances or other devices that incorporate battery backup in their design on that mandated day, however, you might find the number of replacements surprising, the day a long one and the
Why does the current flow? That was the question we left on the table at the end of our last session. We had pretty well nailed down the ampere as being the basic unit of measurement of electric current, in that it describes the quantity of flow of electrons from one place to another. We were about to examine the volt, the ohm and the watt when the current-flow question arose to command our attention. To get a firm handle on this, we are forced to backtrack a bit. Actually, we have to go back a long, long way - about 60 million years, to when a particular species of pine-like trees grew along the Baltic coast. Over the millennia, the resin from those trees became fossilized, producing the beautiful, beer-colored material called anbar by the
