Quiz: How does a light bulb work?

By: Staff
Image: refer to hsw

About This Quiz

What's inside a light bulb? Why don't they burst into flames? What exactly makes a light bulb glow, anyway? Take our quiz to see whether you're in the dark about how light bulbs work.

What was a drawback to using oil lamps for lighting?

People lit their homes with oil lamps for thousands of years before the use of light bulbs. If you visit ancient ruins, you can still see the dirt these lamps left on the walls.

Who was the first to invent an affordable and workable electric light for the home?

Though most people associate Thomas Edison with the electric light bulb, Joseph Swan developed a working bulb a year earlier than Edison did.

When was the light bulb invented?

Swan and Edison each invented a version of the light bulb in the late 1870s.

Twenty-five years after its invention, how many homes around the world had light bulbs?

Light bulbs were inexpensive and easy to make and created no mess that had to be cleaned up. These factors made the light bulb a no-brainer that spread around the world very quickly.

What are light particles called?

Photons are the energy particles that atoms release when their electrons get an energy boost.

Which of these weighs the least?

Photons have no mass, so they don't weigh anything at all. But they move at the speed of light.

When an electron has more energy, will it be closer, farther or the same distance from the nucleus of the atom?

Usually, an electron will move farther from the atom's center only temporarily. Once it releases its extra energy, it will return to its regular distance from the nucleus.

What causes light to be a specific color?

Different types of atoms have their electrons in different places. This changes the wavelengths of the light they release, which determines the color of the light.

How many contacts are on the base of an incandescent light bulb?

The two contacts are in different places; one is on the bottom and one is on the side of the screw threading. The two contacts complete a circuit when you turn the light on.

What is a free electron?

Free electrons are the ones that flow through a solid material in an electrical current. That's why they can't be bound to other atoms.

In an electrical current, in what direction do the electrons flow?

Since electrons are negatively charged, they flow to a positively charged area.

How does electrical current excite the atoms as it flows through a bulb's filament?

Electrons moving through a light bulb filament collide with the metal atoms already there. When the atoms vibrate from these "traffic accidents," they heat up and give off light.

Why is a thinner filament better for lighting than a thicker one?

As electrons move through more resistant, thin filaments, they collide with more atoms and heat the filaments more.

How hot does the filament of a light bulb get?

Before a metal atom gets hot enough, it will release only invisible infrared light. However, at a high enough temperature, around 4,000 degrees Fahrenheit (2,204 degrees Celsius) some of the photons it releases will be as visible light.

If you stretched out the filament in a 60-watt bulb, how long would it be?

The filament is about 6.5 feet (1.9 meters) long but just a fraction of an inch thick. It's doubled up and tightly coiled to fit in a space about an inch (2.5 centimeters) long.

Why is tungsten a good metal to use for light bulb filaments?

Unlike most metals, tungsten does not melt at the high temperatures that light bulb filaments reach.

Why did manufacturers stop sucking the air out of the insides of light bulbs?

When a tungsten atom separates from the filament in a vacuum, it flies onto the inside of the glass. Without a vacuum, its hit another gas molecule and bounces back onto the filament.

What gas fills most light bulbs today?

Since argon is an inert gas, the filament glows without catching fire, as it would with air.

About what percent of the light from an incandescent bulb is actually visible?

Since most of the light that an incandescent bulb emits is infrared, they waste a lot of energy. You might consider fluorescent bulbs or light-emitting diodes (LEDs) if you are looking for an efficient alternative.

What makes a three-way bulb unique?

By using two filaments of different wattages, a three-way bulb can light at three different brightness levels. It can use just the lowest wattage filament, just the brighter or both.

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