Peter Todd Vincent, Age 7 Of East Lansings Mich., for his question:
How does a light bulb work?
We tend to take this bright bit of magic for granted. We can switch on an electric light and in less than a second a dark room becomes light as day. But a hundred years ago this could not be done, and no one could buy an electric light bulb, even with $50 million. It had not yet been invented. The electric light bulb was given to us about 80 years ago by the amazing american inventor.. Thomas Alva Edison.
First let's obey the safety rules. No sensible seven year old would think of breaking open an electric light bulb. The spikes inside and the shattering glass are too risky to handle., even when your curiosity burns to know how it works. In any case, the inside of the bulb could not answer the question. The juice which makes it work is outside.
The powers which is the so called juice to light a bulb., is electricity. And electricity has no smell and makes no sound. Ws cannot see it or touch it. It is . An invisible forces a giant we have tamed. It is made in a far away generator and runs through wires to where it is needed. In your house, the powerful giant is always waiting in the electric wiring.
The job is to get it out of the wires and make it heat a toaster, run the vacuum or light a lamp. To grasp how this is done, we must understand something about electricity. And this takes us down, down to the bitsy world of atoms and the tiny particles from which atoms are made. Electric power comes from atomic particles called electrons.
You can write the number of electrons in a pound. It is the figure 1 followed by 30 zeros. Countless billions of electrons stream through the electric wiring., pushing and josting. The inside of the light bulb has rods and wire threads which are connected to the wiring of the house.
The electric power pushes electrons through the filament threads inside the bulb. The filament is very thin, and the streaming electrons are now squeezed in a traffic jam. They jostle the atoms of the metal filament, and these traffic accidents give off heat and light.
When we turn the switch on, we let the current of electrons into the bulb. They give off light when they are forced through the fine metal filament, when we turn the switch off, we stop the stream of waiting electrons from getting into the electric light bulb.
Most homes use alternating electric current. The streaming electrons hop back and forth through the copper wiring instead of in one direction. Chances axe, the electrons that light your reading lamp jog back and forth 60 times every second.
And it takes about three billion billion electrons jogging 60 times a second to keep your lamp burning.