Electricity is everywhere! That isn’t a joke. Electricity is simply the movement of electrons. Electrons are found in atoms which make up all of the molecules in our bodies, and they are seldom staying still. Getting a bunch of electrons moving the right way to do something useful is more difficult, which is why we haven’t found primitive iPads with fossils of dinosaurs.
That said, electricity can be difficult to describe and understand. Most of us have probably felt electricity in some way. Have you ever shuffled across the carpet in your socks and ran over to one of your friends (or siblings!) in the hopes of giving them a tiny shock? That is actually exactly the same thing that is happening in this video!
To get an understanding of how this works requires delving down into the tiny world of atoms. An atom is made up of three parts: protons, neutrons, and electrons. In an atom, the protons and neutrons live in the center in something called the nucleus. Whizzing around them are the tiny electrons.
These things interact by something called a “charge”. A charge can be either positive (+), negative (-), or neutral (0). Neutral objects don’t have a charge, and don’t interact with other charges. They just hang out. When it comes to the charges, opposites attract! Positive and negative charges are always pulled towards each other. When like charges get together, they repel, or push away. When a whole bunch of like charges get together, they jump away and make lightning!
Electrons are very easy to move around. They are so tiny that you can’t see them, and almost impossibly light. When a balloon is rubbed against someone’s hair or clothing (or socks on the carpet), bunches of electrons get piled onto the balloon. This is because the electrons on the thin fibers of these materials are not held very tightly.
This means that a bunch of electrons are all next to each other. Water is a pretty simple molecule H2O that has a negative side and a positive side. When the water is brought close to the balloon, the negative side of the water molecule is pushed away from the balloon, and the positive side is pulled towards it. Now the positive side of the water molecule is closer to the negative charge on the balloon. What do these opposite charges do? Attract!
Have you ever played air hockey? There is something strangely satisfying about how the puck slides effortlessly across the table, before finally coming to rest. This same thing happens naturally as well, and its actually some pretty cool science. Lets check out how it works!
When things of different temperatures interact, the warmer object loses its heat to the cooler object. This simultaneously warms up the colder thing, and cools down the warmer thing. This shouldn’t be surprising. Its the reason that snow melts in your hands and make your hands feel cold. However, when things are of vastly different temperatures, it can get a little strange.
In the video, we are dripping water onto a stovetop that is around 500℉. The water is only about 50℉, but the important part is that the boiling point of water is around 200℉ (technically 212℉ but Astrocamp is at an elevation of about 5600’, which actually lowers the boiling point to almost exactly 200℉) which is much lower than the temperature of the stove.
When the drops of water hit the stove, the part that hits first is immediately vaporized because of the difference in temperature. This means that the little droplet of water now has a little barrier of water vapor between itself and the stovetop, which it can float around on. The water droplets seem to bounce and skitter around without boiling away. This is what we call the Leidenfrost Effect. For water, this seems to occur at temperatures of at least 400℉.
It is the same thing that allows a person to pour liquid nitrogen over their hand unharmed (Don’t try this at home), or dip their hand in water and then dip it in boiling hot lead (DEFINITELY don’t try this at home)! Cooks sometimes use this to estimate the temperature of their pans and see if they are ready to cook.
The balloon in the video isn’t anything special. It’s a completely normal balloon filled with completely normal water. However, water is quite extraordinary!
We describe matter by listing its different properties. Some of these properties include how dense something is, its flexibility, its ability to conduct electricity, and even its color! Another less commonly known (but just as important!) property is called “specific heat”. This property is one of the things that makes water really interesting!
Specific heat indicates how difficult it is to heat up or cool down an object. For example, if you were to put two pots on a stove and fill one with air (by leaving it empty) and fill one with water, the air one would heat up much quicker even though the stove is adding the same amount of energy to each one! The water doesn’t heat up nearly as much while being given the same energy, meaning it has a very high specific heat.
This is exactly what happens in the video. The match is hot enough to melt the rubber and form a hole, causing the balloon to pop immediately! It actually pops before the fire even reaches the surface.
With the water balloon through, the entire balloon can be engulfed in flame, and nothing happens! This is because the water absorbs the energy from the hot flame, but doesn’t heat up very much. The rubber never heats up enough to melt.
Specific heat works the other way too. Water also takes a long time to cool off. In this way, the specific heat of water actually shapes the climate on a global scale. Take a look at the image below. The snow cycles are much more visible in the Northern hemisphere because they only have to go over land. Ground has a lower specific heat than water, so during the winter it cools down more easily, allowing the cold to pass further south forming ice over most of the Northern continents. In the Southern Hemisphere, the water is much more difficult to cool down, and the icy chill barely even reaches the land!
“A Breathing Earth” by John Nelson, using images from NASA’s cloud free satellite imagery of Earth.