This App Turns Your iPhone Into A Fan. Here's How
Apps, especially iPhone apps, come in all shapes and sizes. They can track your fitness, manage your finances, and help you communicate with the outside world. As wide as app capability may range, each has one underlying point. They add a bit more functionality and usefulness to your already highly functional smartphone. This includes the apps you're unlikely to use every day, including those that fall into the "party trick" category.
Blower is one of those apps. It helps you get additional function out of your phone's hardware, but it isn't something you'll use very often. The app claims it can turn your phone into a fan. It won't be enough to cool you down on a warm day, but it is powerful enough to extinguish a small candle, but way not in the way you may expect. Let's take a look at the Blower app in detail, how candles keep a flame alive, and how you can use your iPhone to blow out the burny things on top of your birthday cake.
What is the Blower app
The creatively titled "Blower" app claims to provide a way for you to use your iPhone to blow out candles. It does this without making any actual physical changes to your iPhone, and the app itself is pretty tiny at 87.6 MB. Blower isn't free, but it is priced at a relatively low $1.99 and works on the iPhone, iPod, and iPad. If you're an Android user wondering why the iPhone crowd seems to be having all the fun, don't worry. Similar apps are available and some of them cost just $0.49. Reviews for the Android versions are mixed though, so you may have to take advantage of the Play Store's refund policy if your phone isn't blowing out any candles.
It contains a small animated fan that spins with the touch of a finger, and whirls away alongside the noise the app makes when you hit the "on/off" button. According to the meter on the app, the fan goes up to 40,000 RPM. This is apparently enough to extinguish a small candle, like the one you'll find on a birthday cake. Bigger flames may prove more of an issue for the app's animated fan.
Why would you want the Blower app? Well, there is no practical use to it. There aren't many situations where you really need to take out a small candle but your lungs or fingers aren't available. But it is an interesting enough party trick, and a sound recognition function means you can use it to remotely blow out a candle if you're virtually attending a birthday party or something.
How blowing out a candle works
There are some misconceptions about how candles are actually blown out. Combustion requires three elements — heat, fuel, and oxygen (via South Carolina University). Take one of these three away, and combustion can't occur. Some people believe the carbon dioxide (CO2) from your breath is enough to snuff out the flame. While there is CO2 in your breath, and CO2 in large amounts will displace oxygen and extinguish a fire, there CO2 to oxygen ratio in your breath isn't actually high enough to do this. Gently blowing on a flame will actually increase the intensity in which it burns because the stuff you exhale still has a pretty high oxygen content. Similarly, you don't blow out a candle by cooling its fuel source. Solid wax won't flow up the wick, but your breath is usually warmer than the air around you, so it's not enough to cool something that's actually on fire at the time. As The Columbia Daily Tribune explains, when we blow out a candle we actually push the flame itself away from its fuel source. No fuel, no fire.
You can get devices that blow. Some vacuum cleaners have a reverse setting, hairdryers are obviously designed to blast air out, and if you're shifting leaves around a lawn you're probably using a device called a "blower." But all of these things have specialist parts that allow them to create that airflow. An iPhone obviously doesn't have fan blades in it, and installing an app doesn't add any hardware to the device. While it may not have a fan capable of throwing out air, it does have a speaker which can, in certain circumstances, do the job.
Soundwaves work a little differently
Sound behaves a bit differently. The term "waves" is apt as sound vibrates the air and pushes it in one direction before it shifts back to where it began. So a sound wave itself isn't able to shift a flame from a wick and put out a candle. However, the sound from your iPhone is generated by a speaker, which moves back and forth pulling in and pushing out air. The amount of air being pushed out and pulled in is always equal, but the air the speaker is pushing out is a little different from what it draws in, and this is how the candle is extinguished.
When we use our mouth or a tool to blow the "air," which is a bunch of spaced out gas particles, tends to head in a single direction. As YouTube channel The Action Lab explains in the video above, this is called "coherent air" and is much more forceful over a short distance than "incoherent air" which is air coming from several directions. When air is drawn into something, it tends to be incoherent air. It is this difference that makes the iPhone app work. The same amount of air is going in and out of the speakers, but the "out" air is coherent, so it is blasted away from the phone in a single direction when the speaker's diaphragm bulges outwards. The same amount of air is then drawn in, but it is pulled from all directions, your speaker doesn't haul the exact same particles it shot out back in. The air being pushed out is enough to shift the flame away from the wick and extinguish the candle, provided the app gets your phone to pump out the correct wavelength and frequency.