One Old Lightbulb (710L)P01_review

You flip the light switch and hear a crisp pop. The room remains dark, which can mean only one thing. It is time to replace the light bulb.

“Mom, I am getting a new bulb out of the closet,” you announce to your mother.

“Let it cool down,” your mother calls back.

She knows you have changed many light bulbs over the last few years. You learned long ago that light bulbs get really hot when they are on.

Imagine a light bulb that seems to last forever. A typical incandescent bulb may only last a few years. There is one bulb in a California firehouse that has broken all the records. It has stayed lit for over 100 years. In fact, it has been burning bright since 1901. The bulb supports the phrase, “they don’t make them like they used to.” But do they? The answer to that is a little complicated.

Until just a few years ago, most light bulbs that were sold were similar to the one in the firehouse. This was called an incandescent bulb. These bulbs emit light as electricity is passed through a carbon filament.

As electrical current passes through the filament, it gets really hot and emits light. You can clearly see the filament in the centennial bulb.

Electric current enters a light bulb, passes through the filament, and then travels back out. This loop through the lightbulb completes the circuit. This allows the bulb to light. When the filament in a bulb breaks, it opens the circuit and electric current will not move.