20 Interesting Facts About Electricity

Electricity is everywhere in society today, and it’s hard to imagine living without it. In fact, it forms the basis of nearly every modern technology, from lighting to supercomputers. But even though it’s so ubiquitous, many people don’t know how it actually works. It’s just something that only catches attention when the power goes out. Well, here are 20 facts about electricity that may just shock you.

1. Electricity and magnetism are interrelated.

A changing electric field creates a changing magnetic field, and a changing magnetic field creates a changing electric field. These two properties are summed up in Maxwell’s equations. They show that electricity and magnetism are part of the same force: the electromagnetic force. It’s one of the four fundamental forces, along with the strong and weak nuclear forces and gravity.

2. That interrelatedness allows electricity to power electromagnets…

A loop of wire with an electric current going through it creates a magnetic field that runs through the middle of the loop. The more loops, the stronger the magnetic field. The strength of the magnetic field is also dependent on the strength of the current. The “north” direction of this field can be found using the “right-hand” rule: curve the fingers of your right hand in the direction of the current flowing through the loop, stick your thumb out (a thumbs-up position), and your thumb will be pointing to it. That’s the basic principle behind electromagnets. The ability of electromagnets to be turned on and off or change strength at will forms the basis of many technologies, such as electric motors, speakers, and maglev trains.

3. …and also works in reverse, allowing magnetism to generate electricity.

This useful property is harnessed in alternators. In an alternator, a changing magnetic field (from a rotating magnet) creates a voltage in a nearby surrounding wire, as shown below.

A basic alternator. Rotating the magnet in the middle of the wire creates a voltage in the wire. Source: Egmason (https://en.wikipedia.org/wiki/File:Alternator_1.svg)

They’re what nearly every kind of power plant uses to generate power. Fossil fuel plants? They burn the fuel to turn water into steam, which turns the alternator in steam turbines (turbo-alternators). Nuclear and geothermal plants? They do the same thing except they use the heat from nuclear reactions and geothermal heat, respectively. Wind turbines and hydroelectric plants? They use the motion of wind and flowing water to turn alternators directly. Alternators are even in your car. They help charge the battery and power the electrical systems when the engine is on.

4. It’s also responsible for Earth’s magnetic field.

What’s the biggest electromagnet on Earth? Trick question, it’s the Earth itself. Earth’s magnetic field is the result of electric currents flowing in the liquid part of Earth’s iron core (the outer core). These currents form from the rotation and convection of electrically conductive liquid (in this case, molten iron alloys). The heat from the core powers the motion, and, due to forces like the Coriolis force as well as feedback effects from the magnetic field the motion creates, the fluid ends up flowing in “rolls”, as you can see below.

The flow of electrically conductive, molten iron alloys in the Earth’s inner core. The blue arrows indicate the flow, while the white arrows indicate the magnetic field lines. Source: USGS

Those rolls are very similar to the coils of an electromagnet and produce Earth’s magnetic field. Similar mechanisms are responsible for the magnetic fields of other planets and stars. In fact, the reason why some planets, like Mars, don’t have a strong magnetic field is because they no longer have enough internal heat to create convection currents within their cores.

5. Electromagnetic induction allows the wireless transfer of power.

A coil of wire with an electric current going through it produces a magnetic field. But can you do the reverse and use that same magnetic field to power another coil? You can! It’s called electromagnetic induction, and it’s the basis of wireless charging technology, induction stoves and cookware, and many other technologies.

Inside a wireless charging pad, there’s a coil of wire with alternating current (AC) running through it that produces a corresponding alternating magnetic field. When you put a compatible device on it, the alternating magnetic field induces AC in a corresponding coil inside the device, giving it power. That’s why devices that are compatible with wireless charging must have a non-metal back plate (usually glass).

6. Light is a self-propagating electromagnetic wave.

As you know, electricity and magnetism are intrinsically linked. A changing electric field creates a changing magnetic field and vice-versa. This allows an electric field and a magnetic field to create a wave that can propagate without a medium. The following animation shows this in action.

The structure of an electromagnetic wave. E, in red, is the electric field. B, in blue, is the magnetic field. λ is the wavelength. Source: Lookang (https://en.wikipedia.org/wiki/File:Electromagneticwave3D.gif)

All forms of electromagnetic (EM) radiation, including visible light, are these electromagnetic waves.

7. Electric current is moving electrons.

Well technically, any flow of charged particles (positive or negative charge) creates an electric current. But the electricity that everyone is familiar with is the result of electrons moving in wires. The reason why metals are such good conductors is that metal atoms usually have one or more loosely bound electrons. These electrons can move freely within the metal.

Normally, those free electrons bounce around randomly. That’s why a wire that isn’t connected to anything has no current. But when you connect a power source (basically an external electric field), the free electrons move in a more organized direction, creating an electric current.

8. Alternating current (AC) is better than direct current (DC) for transporting electricity in most cases.

With DC, the current only moves in one direction. That’s good for most electronic devices because they need a stable current to work. But DC is generally not cost-effective for transporting electricity through power lines. Transporting electricity efficiently requires very high voltage. By increasing the voltage, you decrease the current needed to deliver the same amount of power. That lower current translates to less power lost as heat from the resistance of the power lines. It’s not easy to change the voltage of DC, making it more expensive than AC in most cases.

In AC, on the other hand, the electrons move back and forth resulting in a current that oscillates. This allows the voltage of AC to be changed relatively easily by using a transformer. Power from power stations is transported as very high voltage AC and then transformed to a much lower voltage before it goes into houses and buildings.

The case where DC is better than AC for transporting electricity is for very long distances. High-voltage DC (HVDC) equipment is costly, but over those distances, it becomes cheaper than AC because AC requires more infrastructure to maintain it. It also loses less power than a comparable AC system.

9. Electricity in cables travels at close to the speed of light…

When electrons move in a single direction to form an electric current, their electric fields, which move with them, affect other electrons down the wire. Electrons repel each other, so the result is an electromagnetic field fluctuation that propagates down the wire. You can think of it as a bunch of people in a line. Each person pushes the person in front of him or her when pushed. When the last person in line pushes the person in front of him or her, it sends a “push wave” all the way down the line very quickly. The individuals represent electrons in the wire, and the “push wave” is the electromagnetic field fluctuation.

This fluctuation is what carries electrical energy and signals, and it travels at nearly the speed of light. The reason it doesn’t travel at the speed of light like EM waves is because it’s a result of electron interactions and not a standalone EM wave.

10. …but the moving electrons that create it travel much slower.

The speed of the overall electron flow is the drift velocity, and it’s very slow. Like literally snail speed slow (on the order of a few mm/s). That’s because although individual electrons move very quickly, there are a lot of atoms in a dense material like metal. To electrons, the atoms are obstacles, so it’s difficult for them to move in the direction of the flow in a straight line (they bounce around between atoms).

11. Static electricity is dangerous for electronics.

Static electricity to us is usually just the occasional annoying shock or messy hair after putting on a sweater. But to electronics, they can cause serious, permanent damage. Many electronic components, especially microchips and their semiconductors, are very sensitive to static. That’s why manufacturers of electronics, computer repair workers, and engineers who work with electrical components take numerous precautions to guard against it. Some of these measures include anti-static bands, anti-static bags, and controlling humidity (humidity can’t be too low).

12. Some substances can generate electricity when under mechanical stress.

This effect is known as piezoelectricity, and it’s used in plenty of places. For example, it’s in the motion sensors of smartphones and certain video game controllers (ex. Wii Remote). When you move them, the acceleration causes the piezoelectric components of the sensors to bend slightly and send a signal to the devices. That allows the devices to know how you’re moving or tilting them.

It’s also how quartz clocks work. When an electric field is applied to a specially cut piece of quartz, it vibrates with a specific frequency (a reverse piezoelectric effect). That vibration creates electric pulses as the quartz crystal flexes (a piezoelectric effect), which the clock’s circuitry turns into a frequency that the clock can use to drive the hands of the clock (usually seconds).

13. Everything except a perfect vacuum can conduct electricity if the voltage is high enough.

The process usually involves the material changing in such a way due to the high voltage that it now conducts electricity. It’s called electrical breakdown, and the specific process is different for different materials. The voltage at which electrical breakdown occurs is the breakdown voltage.

In fact, you’ve probably experienced this yourself. Whenever you get shocked by static electricity, it’s because the air between your skin and the thing that shocked you suffered an electrical breakdown and stopped being an insulator. The voltages involved in these shocks is on the order of thousands of volts (but the currents involved are tiny).

Theoretically, a perfect vacuum can’t conduct electricity because there’s nothing there to carry the electric charge. But some materials can start to shed electrons at high voltages, creating an area within the now not-so-perfect vacuum that can conduct electricity.

14. Electric fields are very strong around pointed objects.

It’s because around pointed tips, there are more electrons packed together. Think of it like this. Assume there’s this flat sheet that’s one electron thick. Electrons repel each other but also must stay in the sheet. So, they repel each other and spread out in the sheet until they reach equilibrium. In this case, the repulsion force (acts in the direction of the line that connects two electrons) is completely parallel with the sheet, meaning all of the force is directed at other electrons in the sheet.

Now bend that sheet so that has a point. The force repelling two electrons on either side of the point is now mostly pointing in the direction perpendicular to the sheet. That means there’s much less force repelling those electrons away from each other. So, they tend to cluster more at the point. Obviously nothing in real life is just a sheet made of electrons, but the same mechanism happens in pointed objects, such as lightning rods. That’s why lightning tends to hit those kinds of objects much more frequently.

15. The US is one of the few countries using 120 V.

Most of the rest of the world uses a mains voltage of around 230 V. The US, Canada, and a handful of other countries are the only ones that use a voltage of around 120 V. What voltage a country decides to use is mostly due to historical convention. Once a country starts using a particular voltage, it’s very difficult to rebuild the entire system around another voltage.

You should always check to see what voltage countries that you’re traveling to use before sticking an appliance into a socket. For example, most power supplies in desktop computers have a switch to change it from the lower voltage to the higher one. If you don’t have the right setting for the country you’re in, either the computer won’t work (set to the higher voltage when mains voltage is the lower one) or you’ll fry the computer (the opposite).

16. The US produces about 4.12 trillion kWh of electricity every year.

It’s the second largest producer of electricity in the world under China, which produces about 7.11 trillion kWh a year. Most of the electricity in the US comes from fossil fuels (about 63%). The rest comes from nuclear (about 20%) and renewable sources (about 17%).

17. But we waste a lot of that electricity.

In fact, we lose 5% just from transmitting and distributing the electricity. The average residential or commercial building wastes about 30% of the electricity it consumes (ex. lighting and appliances that are on that don’t need to be). You can help the problem by installing energy efficient appliances and lighting. They can improve the efficiency of the structure by 10-35%.

18. LEDs are one very good way to reduce electricity usage.

They use about 75-80% less electricity than traditional incandescent light bulbs and last 25 times longer. They’re also slightly more energy efficient than fluorescent light bulbs and last about 2.5 times longer. All these translate to savings on your electricity bill.

19. Peaking power plants help keep the electrical grid stable.

As you probably know, drawing too much power from the electrical grid will cause a brownout or blackout. To keep up with demand that can sometimes spike suddenly (ex. lots of air-conditioners turning on), grid operators turn on backup power plants during peak hours. These are peaking power plants. However, these plants are more expensive to run because they aren’t as efficient as regular plants (too expensive for just intermittent use). That higher cost is partly the reason why electricity costs are higher during peak hours.

20. Triscuit gets its name from electricity.

Ever wondered how those shredded wheat crackers got their name? Well it turns out that the original product, which was first produced in 1903 by the Natural Food Company (later renamed The Shredded Wheat Company) in Niagara Falls, NY, was advertised to be the only food “Baked by Electricity” on the market, as shown below. The name for such a food? Triscuit, a combination of “electricity” and “biscuit”.