1. The word ‘electric’ comes from the Greek elektron, amber. Rubbing amber with wool or fur produces static electricity and the amber attracts small pieces of ash or paper. The Greeks thought it was a form of magnetism in non-metals. It wasn’t until 1600 that it was recognised as different.
2. Lightning is a giant spark of static electricity, although the details on how it works are still unknown. All atoms have a positive nucleus in the centre and negative electrons around the outside. In some situations, like rubbing amber, some electrons can be stripped off and temporarily attached to other atoms. This gives you an unbalanced charge when the materials are separated, with one positive and the other negative. They need to touch something else for more electrons to move and the charges balance. Sometimes the electrons will jump a gap and we see them as a spark. How far they can jump depends on how strong the charge difference is.
In lightning a difference in charge builds up in a cloud or between a cloud and the ground. It is unknown how it is triggered, but the imbalance is strong enough that the spark, or lightning, can make the enormous leap.
3. Transformers have shaped the way we generate and use electricity, the way power grids work and our safety with electric devices. Transformers rely on something called induction. I’ve mentioned before about the link between movement, magnets and electric current. In a transformer you put current through an electric coil, producing a magnetic field. Then you have another coil next to it and the magnetic field will produce a current in that coil. The trick is that you can wind the coils more or less to change the voltage in the second coil.
Transformers are used to step voltage up or down. For efficient long distance transmission of power it needs to be high voltage and low current, so massive transformers have literally created our energy grids. They allow a single power station to send electricity to distant locations. Without transformers we would need many small, close power stations.
There are also transformers in all electrical equipment. They step the high voltage of mains power down to the voltage that the circuits of the appliance can handle, and isolate us from the more dangerous mains power.
4. We have electricity in our bodies because of how salts dissolve. We know that table salt is sodium chloride, NaCl, and can use that as an example. When NaCl dissolves it splits into positive Na+ and negative Cl- ions. Cells have sophisticated ways of controlling how much of different ions are inside, and resting cells are all slightly negative because they have more negative ions than the surrounding fluid.
When a nerve cell is stimulated it will open or close gates to allow different amounts of sodium and potassium to move across the cell membrane and change the charge. Nerve cells are like wiring in your body – they have very long arms that communicate between your extremities and your brain. And just like a wire, when there is an electrical change in one end it spreads along the cell, taking the signal with it. This is how nerve signals travel so quickly through your body.
This is the reason it’s so important to maintain the right balance of things like sodium and potassium in your body. Sweating and diarrhoea don’t just take water out, they also take electrolytes out and that’s why children who are sick are given a replacement drink rather than plain water. It’s also the mechanism behind water intoxication, where people drink so much plain water they upset the balance of electrolytes in their brain.
A special use of electricity in your body is the sinoatrial node, the pacemaker for your heart. It was proven that hearts do not rely on the brain to beat when a frog heart was isolated in a jar of electrolytic solution and beat on its own. The SA node sends waves of electrical activity around the heart, causing the muscle cells to contract. When people are fitted with a pacemaker this is what is being replaced.
5. The critter up the top is a platypus, and along with echidnas they are the only mammals to use electricity for electrolocation. They hunt for small crustaceans in the mud of river bottoms, closing their eyes, ears and nose when they dive. The electroreceptors are in their bill, which they sweep from side to side in the mud. Their prey produce tiny electrical currents from muscle contractions when they move, just like electrical currents are produced in our own bodies. This helps the platypus tell them apart from rocks and mud.
You can see it in this movie, and look how enormous those flippers are!
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