How Do Fireworks Actually Work?

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iStock

by Sarah Dobbs

Each year, as the Fourth of July approaches, the sound of explosions starts to become a normal part of the evening. Fireworks have existed in one form or another for around 1000 years, and they show no signs of going away anytime soon. But how do they work? Most of us just know to light the fuse and stand back. Let’s take a closer look …

ROCKETS

fireworks over new york city
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Rocket-type fireworks can produce all kinds of different effects when they go off, but the basic structure of an aerial firework stays more or less the same. Each rocket is made up of the following parts: a mortar, fuses, propellant powder, a shell, a bursting charge, and a collection of "stars." The mortar is the outer container, and the fuse is, of course, the piece that you light. When the fuse burns down, the propellant ignites and shoots the firework into the air.

When it’s airborne, a second explosion is triggered inside the shell by a time delay fuse. The bursting charges set off the stars—small, explosive pellets made of fuel and metallic compounds that create the lights in the fireworks display. Different metals create different colors when they ignite: barium goes green, calcium salts go orange, magnesium goes white, copper is blue, lithium turns red, and sodium becomes gold. And the arrangement of the stars will determine the shape of the explosion—so if they’re packed in a heart shape, they should reproduce that heart shape in the sky.

Other effects can also be built in by adding various ingredients; different kinds of fuel can create sound effects, for example, like the whistling or screaming noises some rockets make as they shoot into the sky. Stars can be made up of layers of different metallic compounds, to create multicolored explosions. And in some more complex fireworks, there may be several stages of explosions; in that case, there are generally multiple fuses inside the shell, and as each burns down, a different explosive goes off.

FOUNTAINS

fountain type fireworks
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Of course, not all fireworks are of the shoot-into-the-air-and-go-bang variety. Fountains don’t take off, and generally don’t go bang, either; instead, they stay where they’re placed and give off a cascade of sparks—like a fountain, but with pyrotechnics instead of water.

Usually conical in shape, fountains consist of a paper or plastic tube, with clay plugs at either end. Inside the tube are a couple of different kinds of fuel, plus the metal compounds that create the sparks. When the fuse is lit, the fuel ignites, and sparks are forced out of an aperture in the top of the fountain.

Again, different metals create different colors and effects. Multi-stage effects can be created by bundling multiple tubes together, so that as one finishes another starts, adding different colors or sound effects to the display.

CATHERINE WHEELS

wheel firework
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Catherine wheels are another common type of firework, and again the same kinds of ingredients are used to create a slightly different effect. Named for the unfortunate Saint Catherine, these fireworks are generally fixed to a pole or a mount, so that they can spin as they burn, creating a spiral of sparks.

Bigger Catherine wheels tend to have a plastic disk at their center, with “gerbs” attached around the edge. The gerbs are similar to fountains, in that they’re tubes filled with the mixture of ingredients that create the effects; when lit, the thrust from the explosives makes the wheel turn as they burn. And again, the effect can be made more elaborate with multi-stage effects and different colors; each gerb might be different, so that the wheel changes as each one ignites in turn.

Smaller Catherine wheels might, instead, be made up of a single long, thin tube coiled into shape around a smaller central disk. Again, the thrust of ignition makes the wheel spin.

SPARKLERS

person holding sparkler
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The only firework you should ever hold in your hand once it’s lit is a sparkler—a Fourth of July staple. Unlike most other fireworks, they don’t explode with a bang, but gently fizzle for around a minute, as a ball of sparks makes its way down a metal wire. And they’re pretty simple: basically, the metal wire is dipped into a pyrotechnic compound that’s made up of a metallic fuel, an oxidizer, and a binding material.

The metallic fuel is what creates the sparks; it’s usually aluminum or magnesium, which creates white sparks, but some sparklers may use iron or ferrotitanium for gold sparks instead. The oxidizer, which provides the oxygen to keep the spark going, is generally potassium nitrate. And then a binding material, a kind of flammable starch, keeps the mixture together, and burns away once the sparkler is lit.

Hopefully, none of that has taken away any of the magic of a good fireworks display. If nothing else, you’ll be able to impress your friends by quietly musing “oooh, barium” next time you see a green firework.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

What Do the Terms on Energy-Saving Light Bulbs Mean?

Scott Olson, Getty Images
Scott Olson, Getty Images

There's a reason your parents used to scold you for not turning off a light when you left a room. According to the U.S. Department of Energy, an average American household uses up to 5 percent of their total energy expenditure on lighting. Living rooms get flooded with light. Dining rooms and dens are full of lighting accents. Motion lights, hallway lights, bathroom vanity lights, lamps—we like our lives to be nice and bright.

Fortunately, energy-saving lighting sources have largely replaced the conventional incandescent bulbs that once used up a substantial amount of power. Those bulbs heated up a coil, or filament, of tungsten wire that gave off light. Roughly 90 percent of the energy they passed on was in the form of heat, which siphoned off energy and kept utility bills inflated. Today's bulbs brighten without the waste. That's the good news. The bad? The varieties of bulbs can be confusing. If you've ever been lost in the fixtures section of the hardware store, here's a quick primer on what these terms mean.

Halogen Incandescent:

These are incandescent light bulbs that contain a halogen gas-filled capsule around the filament to help increase energy efficiency. While cheaper to operate than a conventional incandescent bulb—they use 25 to 30 percent less energy—they don't produce as much of a cost savings as other options. On the plus side, they reach full brightness immediately. Other choices may take time to warm up.

Compact Florescent Lamp (CFL):

When you see a coiled light bulb, it’s likely to be a CFL, which is simply a downsized version of the tubular florescent lighting seen in commercial spaces. Instead of an electric current traveling through a filament like in an incandescent bulb, the current goes through a tube containing argon and mercury vapor. The resulting ultraviolet light activates phosphor inside the tube, which emits light. It uses one-third of the energy of a halogen incandescent. The downside? They can take a little time to warm up, especially if used outdoors. They also contain mercury, a potential health hazard if the bulb breaks. (See the "mercury" entry below.)

Light Emitting Diode (LED):

This type of bulb uses a semiconductor to convert electricity into light. In addition to being energy-efficient, they usually last eight to 25 times longer than halogen incandescent bulbs and four to eight times longer than CFLs—perhaps as long as 18 to 46 years. You'll probably pay more up front, but the expense is offset by their durability. Most LEDs are compatible with dimming switches, too. Most CFLs aren't, so if that's important to you, you'll want to stick with LED.

Energy Star:

A bulb with an Energy Star label was evaluated by a third party to make sure its energy-saving claims are accurate, and they'll typically have a longer warranty than bulbs without the endorsement.

But what about the "nutritional label" style information box that appears on light bulb packaging? Let's take a closer look.

An example of a label that appears on energy-efficient light bulb packaging is pictured
Federal Trade Commission

Brightness:

You have probably inferred that brightness refers to the light output given off by a bulb. This is measured in lumens and rounded off to the nearest five. (A bulb will never be 822 lumens. It's 820.) The higher the number, the brighter the bulb. Since you're probably used to shopping by wattage, consider that a bulb with 800 lumens is roughly the equivalent of a 60-watt incandescent. A 1100 lumen bulb will resemble a 75-watt bulb.

Estimated Energy Cost:

This is a rough estimate of much it will cost an average household to operate the bulb. What's average? The wattage of the bulb is calculated with three hours of daily operation at a cost of 11 cents per kilowatt. Your actual cost will go up or down whether you use it more or less or pay your energy supplier a different amount.

Life:

This is how long the bulb is expected to last based on the same usage estimated for the energy cost and rounded to the nearest tenth of a year.

Light Appearance:

This refers to the color temperature of the bulb measured in Kelvin, a temperature scale measuring light color. The range is from 2600 K (yellow and warm) to 6600 K (blue and cool). Bright white is about 3500 K. You should probably avoid anything above 3000 K for any interior room.

Energy Used:

This is how much energy the bulb will require and is measured in watts. The lower the wattage, the cheaper it costs to operate. This is where the energy savings materializes, as a 10-watt LED bulb may give off as much light as an old 60-watt incandescent.

Color Rendering Index (CRI):

It's not on all bulb packaging, but if you see it, it refers to how accurate colors will appear under the bulb's light on a scale of 0 to 100. Halogen incandescent bulbs score high. CFLs and LEDs aren't quite as accurate, though they may still get the job done. Try to get a high CRI if you'll be using the bulbs in a bathroom, as skin tone can appear off with lower CRI numbers.

Mercury:

You might see some CFL bulb packaging with a mercury disclosure. This isn't an issue if the bulb remains intact, but if it breaks, it might release potentially hazardous mercury vapor and the introduce the very small possibility of mercury poisoning. Avoid using CFL bulbs in kids' rooms if there's potential for knocking over a lamp or light. Broken bulbs that contain mercury should be cleaned up by following Environmental Protection Agency guidelines—picked up with tape, not vacuumed—and disposed of properly. Old bulbs should be recycled.

Does the Full Moon Really Make People Act Crazy?

iStock.com/voraorn
iStock.com/voraorn

Along with Mercury in retrograde, the full moon is a pretty popular scapegoat for bad luck and bizarre behavior. Encounter someone acting strangely? Blame it on the lunar phases! It's said that crime rates increase and emergency rooms are much busier during the full moon (though a 2004 study debunked this claim). Plus, there's that whole werewolf thing. Why would this be? The reasoning is that the Moon, which affects the ocean's tides, probably exerts a similar effect on us, because the human body is made mostly of water.

This belief that the Moon influences behavior is so widely held—reportedly, even 80 percent of nurses and 64 percent of doctors think it's true, according to a 1987 paper published in the Journal of Emergency Medicine [PDF]—that in 2012 a team of researchers at Université Laval's School of Psychology in Canada decided to find out if mental illness and the phases of the Moon are linked [PDF].

To test the theory, the researchers evaluated 771 patients who visited emergency rooms at two hospitals in Montreal between March 2005 and April 2008. The patients chosen complained of chest pains, which doctors could not determine a medical cause for the pains. Many of the patients suffered from panic attacks, anxiety and mood disorders, or suicidal thoughts.

When the researchers compared the time of the visits to the phases of the Moon, they found that there was no link between the incidence of psychological problems and the four lunar phases, with one exception—in the last lunar quarter, anxiety disorders were 32 percent less frequent. "This may be coincidental or due to factors we did not take into account," Dr. Geneviève Belleville, who directed the team of researchers, said. "But one thing is certain: we observed no full-moon or new-moon effect on psychological problems."

So rest easy (or maybe not): If people seem to act crazy during the full Moon, their behavior is likely pretty similar during the rest of the lunar cycle as well.

This story was updated in 2019.

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