# Page:Popular Science Monthly Volume 45.djvu/641

The energy of any current is determined by and is equal to the product of two of its properties, its volume or ampèrage and its pressure or voltage. Letting C represent the ampères and V the voltage, we have that the energy ${\displaystyle =}$ C V. In passing any current over any wire there is a loss of voltage determined by and equal to the product of two things—i. e., the ampèrage of the current and the resistance of the wire; so we have loss of voltage ${\displaystyle =}$ C R. Now, if we have two currents—one, say, of ten ampères and one volt, and the other of one ampère and ten volts—the energy will be the same, or ten watts as it is called. If we pass both through a given resistance, R, we shall have a loss of voltage (${\displaystyle =}$ CR) ten times greater in the first than in the second case. But a given loss of voltage amounts to only one tenth as much energy (C V) in the second case with C ${\displaystyle =}$ one ampère as it does in the first with C ${\displaystyle =}$ ten ampères, so that with only one tenth the given loss of voltage the energy lost will be only one one-hundredth that lost in the first case. What it amounts to is that the loss in passing a given amount of electrical energy through a given resistance is proportional to the square of the current, or amperage, and consequently inversely proportional to the square of the pressure, or voltage.