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Published on
January 21st, 2021

The More You Know: How Does a Light Bulb Work?

Have you ever wondered: how does a light bulb work? It might sound like a piece of relatively useless trivia, but actually, this is a helpful bit of information. This article explains how incandescent, fluorescent, and LED bulbs work. Once you understand the simple science behind each, you can make the best decision about what type of bulb to use in your buildings. Pro hint: choosing the right type of bulb can save you money in the long term!

How Incandescent Light Bulbs Work

Energy at the atomic level

Most people are more familiar with the inner workings of old incandescent bulbs, or at least their appearance, which hasn’t changed all that much since the early days of home electricity. You’ve probably had the experience of having a bulb burn out and hearing or seeing the loose filament inside. That filament is key to the operation of the bulb.

You probably also recognize the screw-in base of a light bulb. Housed in the base are two metal contacts that connect with the electrical circuit supplying power to the fixture. Two stiff wires run between the contacts and the bulb’s filament, which is made of tungsten.

When electrical current flows, it moves between the two contacts by way of the stiff wires and the filament. Electrical current is nothing more than the movement of free electrons, which are one type of subatomic particle. The electrons bump into the atoms of the filament, and those little collisions cause the atoms to heat up.

The atoms begin to vibrate, and they’re momentarily boosted to a higher energy level. Then, they fall back to their normal energy state. So, what happens to that extra energy? After all, energy cannot be created or destroyed, according to the laws of physics. It can only change form.

The leftover energy is released in the form of photons, or light units. The light given off, if enough heat is generated in the process, is visible to the human eye.

Now wait a minute, you might be thinking. Isn’t tungsten highly combustible? Why don’t light bulb filaments catch fire if they’re made of tungsten heated to such a high temperature?

The answer to that question lies in understanding combustion reactions. In order for combustion to take place, you need three things: a fuel (tungsten), heat (created by the current), and oxygen. Light bulbs remove oxygen from the equation by housing the filament in a tightly sealed, oxygen-free chamber. Nowadays, inert gasses, like argon, are added to further reduce combustibility.

How do three-way bulbs work? They use two filaments instead of just one. By turning up the switch on a fixture, users can choose between one or the other of the filaments in the circuit, or they can use both, allowing for three different levels of brightness.

Halogen bulbs, by the way, are a type of incandescent bulb. They simply use less electricity to produce more light because a halogen, such as iodine or bromine, is added to the inert gas in the bulb envelope.

How Fluorescent Lamps Work

A different atomic reaction

Fluorescent lamps also utilize a sealed tube, which contains argon and trace amounts of mercury. The tube is coated lightly with phosphor powder, a material that luminesces when exposed to an electron beam. Electric current flows through electrodes at either end of the tube, which connect it to the power circuit.

The voltage applied when the lamp is turned on makes electrons move from one end of the tube to the other through the argon gas. In the process, they collide with mercury atoms.

As with incandescent bulbs, the electrons’ energy levels are momentarily raised. When they return to their normal energy level, they give off photons as well. These photons are not on our visibility spectrum, but when they interact with the phosphor powder in the tube, they produce white light that can be seen by the human eye.

How LED Bulbs Work

Light-emitting diodes

Light-emitting diode bulbs, known more commonly as LED bulbs, harness a completely different method of producing light. Electrical current is passed through a diode, which is a semiconductor. A semiconductor is simply a material that is not as good of a conductor as substances like silver or copper, which are excellent conductors.

Electrons move across the semiconductor when power is applied to it. As with other light bulb reactions, energy is increased and then released in the form of photons or light that we can see.

You may have seen filamentous LED lights. These look like incandescent bulbs but the filament is actually lined with light-emitting diodes. This has allowed LED bulbs to be used in light fixtures where previously only incandescent bulbs would work.

Why Using Modern Bulbs Saves Energy

Less energy required to produce light

One of the great advantages of fluorescent and now LED light bulbs is that they do not require heat to produce light. This means far less energy is expended to power them, and that means they’re better for both the environment and your wallet as a property owner. Although LED bulbs cost more upfront, not only are they less expensive to run, they last longer too, often years beyond incandescent models.

Are you interested in swapping out your old incandescent bulbs for newer, more energy-efficient ones? We’re here to assist you. Call Bolt Electric today, or use our easy online form to schedule an appointment.

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