Diane Alexander, age 12, of Tecumseh, Neb., for her question:
HOW DOES ELECTRIC CURRENT GET INTO A CORD?
This remarkable happening occurs when we plug an electric cord into an electrical outlet. The cord may be attached to a lamp or a toaster with a separate switch. The gadget lights up or heats up when we turn the switch on and stops working when the switch is turned off. Obviously the magic must be in the outlet because when the cord is unplugged the gadget refuses to work.
People learned to use electricity before they knew how it works. Even now nobody understands all the details. But we do know how household current gets from an outlet into an electric cord. This is merely a small sidestep in a gigantic system of power lines that runs to and from a generator.
Electricity is the energy of moving electrons. Normally a family of these mini particles orbits an atom in orderly traffic lanes. Some can be pried loose, especially theloners in outside lanes. Electric wires are made of copper because the copper atom has a lone electron in an outside lane, all set to leave home.
In a spinning generator, coils of copper keep cutting through the force field around a mighty magnet. For reasons unknown, this creates a jolt called voltage. And voltage pushes zillions of free electrons through electric wires.
However, the copper wires must form an unbroken circuit, a loop with its two ends attached to the generator. Electric wiring has a double strand of copper wire to form a loop. When its two ends are connected with a generator, voltage power zooms through the unbroken circuit and zillions of hopping electrons produce current.
The great power system is carried far and wide and stepped down to supply cities and household current. Along the way there are outlets where current can be tapped from the main circuit. When you plug in a cord, its two prongs open a little gate and current surges through its double strand of copper wire.
Actually, the cord is a small circuit plugged into the larger circuit of household current. The far end of the cord has a gadget to put the electric energy to work. In a lamp bulb, the streaming electrons are crowded through a fine wire filament. This frantic traffic jam causes heat and the glowing hot filament sheds light. The prongs and the outlet open a gate to let household current through the cord. An extra switch can open or close the circuit.