Hello again, fellow hackers! As promised, here is part 2 of my fresh electricity and electronics for hackers series. In this series, we will be making a lot of things, from power supplies to (hopefully) EMP bombs. But before we can build skyscrapers, we first need a foundation. So in the first parts of this series, I will talk about the basics laws of electricity. In this part, I will talk about what electricity is, in what other forms of energy it can be converted, what voltage, current, and electrical resistance means, the different parts of an electric circuit, and last but not least: the effects of electricity on the human body. So with that out of the way, let's get started!
To understand what electricity is, we first need to understand a few things about atoms. Atoms are everywhere in everything, and consist of 3 things: neutrons, which are neutrally charged particles, protons, which are positively charged, and electrons, which are negatively charged particles. the core of an atom are protons and neutrons, and around that core are electrons orbiting it. An atom looks like this:
This atom is neutrally charged. How can we tell? The red dots are protons, the blue dots are neutrons, and the gray dots are electrons. The amount of protons and electrons are equal, so there is no imbalance.
And this is exactly what electricity is: an imbalance in protons and electrons. When an atom contains more electrons than protons, it is negatively charged (-), and when an atom contain more protons than electrons, it is positively charged (+). The atoms will try to regain a neutral state, so the electrons that are excessive in the - pole, will try to go to the + pole. It is this flow of electrons that we call electricity, or more specifically current.
The greater the imbalance between positively and negatively charged atoms, the greater the "pressure". This "pressure" is known as voltage. This also means the greater the voltage, the faster the electrons will flow. The only thing that can slow down a flow of electrons is electrical resistance. This is basically Ohm's law, which we will cover later in more detail.
Alright, we already learned a lot: we know that electricity is simply an imbalance between protons and electrons. Now you also know what the + and - terminal on your battery means and what the "9V" (9 Volt) on it means!
You might have been deceived in elementary school when you first saw a battery (or at least I was): electricity doesn't go from + to -, but it actually goes the other way around! Technically, this is correct, but electrical engineers (and therefor we), like to think electricity goes from + to -, to simplify our calculations. I too will always think electricity goes from + to -, but just know that it is actually the other way around.
Electricity is a form of energy, but there are more forms of energy, like:
- Thermal (heat) energy. Example: a furnace.
- Potential energy. Example: a stretched bow.
- Kinetic (movement) energy. Example: you running.
- Light energy. Example: your screen right now.
- Chemical energy. Example: coal and other fossil fuels.
- And more...
Why am I telling you this, and why does it matter? I tell you this so you will realize why we use electricity. Let's take a look at how electricity is generated and consumed:
- At a power station, coal is burned to make heat (chemical energy -> thermal energy).
- The heat from the burning coal evaporates water, turning it into steam. That steam then drives a turbine (thermal energy -> kinetic energy).
- The turbine drives an alternator (alternator = a generator that generates AC electricity), which produces electricity (kinetic energy -> electric energy).
- The electricity travels on the electricity grid to the consumer, who uses it to cook his food with an electric furnace (electric energy -> thermal energy).
If you look carefully, you can see that electricity simply functions as a way to transport energy. Also, not all electricity received is turned in what it should be supposed to do. This is known as "loss". For example: your computer uses electricity to do calculations, but in the process also generates heat. that heat isn't something we want (fun fact: a high end gaming computer converts electricity into heat more efficiently than a space heater). The same can be said about a classic light bulp. The classic light bulp is ment to convert electric energy into light energy, but it emits more heat than light! Even LED lights have a loss of energy, even if it is very tiny. The loss of energy isn't always in the form of thermal energy. An example: your washing machine's electric motor. It is ment to turn electricity into kinetic energy, but it also makes noise, which means that some of the electricity is converted into sound energy (yes, sound energy is a thing). You don't want this noise, so that also is considered a loss.
Alright, now that we've talked about the different forms of energy and that there is no such thing as "100% energy efficient", let's move on.
I will talk more about the units of electricity in the next articles, but here is a quick introduction to them:
Electrical voltage Is the potential difference between positively and negatively charged atoms. This unit uses the capital "U" as it's symbol and is expressed in Volt, which is abbreviated with the capital "V"
Example: U = 10V means: the electrical voltage equals 10 volts.
Current is the amount of electrons going through a conductive material (a wire, for example). Current uses the capital "I" as it's symbol and is expressed in the unit Ampere, which is abbreviated with the capital "A".
Example: I = 4A means: The current is 4 Ampere.
Electrical resistance is the amount of resistance electrons experience on their way through a material. You have isolators (rubber,plastic...), which blocks electricity completely and has an infinite amount of electrical resistance. Then there are resistors, which allows electrons to pass through, but still have an electrical resistance (like graphite). Then there are conductors, which don't have any resistance at all (like copper or silver) (technically, conductors do have a little resistance, but it is very VERY small). Electrical resistance uses the capital "R" as it's symbol, and is expressed by the unit Ohm. It is abbreviated with the Omega sign. Because WHT doesn't support the omega sign, i'll just use "Ohm". We will learn more about resistance when we cover Ohm's law.
Example: R = 30(Omega sign) means: The electrical resistance is 30 Ohm.
These are the 3 most basic units in electrical/electronic engineering. There are more units, but we will cover those later on.
1: The source. This is where the electricity comes from. In this case it is a battery, but it could also be a generator or alternator. the symbol of a battery is 2 vertical lines, the longer one being the +, and the other being the -. Then from there are 2 horizontal lines, one on each vertical line, representing the + and - terminals of a battery.
The battery on the left is a single-cell battery, the one on the right is a three-cell battery.
2: The conductors. These are the lines in a schematic that connect the battery with our resistor. These are usually wires or tracks on a PCB in the real world
3: The consumer The consumer is the thing that converts electric energy into something else. In this case, it is just a simple resistor with a value of 50 Ohm. Things that consume electricity always have a resistance, so resistors are essentially consumers. A circuit MUST have a consumer, or else we will get a short circuit! Because i am European, I will use the European symbol of a resistor in my schematics. I won't post a picture of a consumer because a consumer has many symbols, Depending on what it is.
The last part of this article: the effects of electricity on the human body. Surely, you know that electricity is deadly, especially in high voltages. But do you know what actually happens when you get electrocuted? That is what i will show you now.
You might have heard that it is the voltage that kills you, but technically, this is not true. It is the current that kills you. Voltage plays a role, but we will cover that in my next article, because that is Ohm's law. Now the question is: why would electricity want to flow through us?
Electricity is lazy. It will always try to find the fastest way with the least resistance, either to the ground (think about lightning) OR to the opposite pole. When you touch a wire that is alive, you are the shortest way to the ground, so electricity will flow through you. Humans and all other living things are resistors: they have a resistance higher than 10 Ohm, but still conduct electricity. Let's have a look at how many amperes cause what effect to your body:
1mA: This amount of current will give you a light, tickling sensation.
2mA: You will get a light shock, but it will still hurt a little.
5mA: The GFCI will trip. A GFCI is a circuit breaker that secures an electric installation. It will trip when it detects electricity is going to an unintended path, a.k.a your body. we will talk more about the GFCI later in this series, as well as how to exploit it to cause blackouts.
10mA: This is the moment the electricity starts taking over your nervous system. Your muscles won't respond to your brain's signals (which is also electricity in a small amount) to get your hand of the wire, because the electricity will overpower those signals. you are "glued to the wire".
20mA: The electricity takes over your nervous system even further: all your muscles will begin to contract and you will start doing random, uncontrollable movements.
30mA: The electricity goes to your lungs. at this stage, suffocation is possible. 30mA is often seen as the border between life and death. At this stage, you will also gain burns
60-90mA: The possibility of suffocation increases.
100mA: Your heart rate is controlled by electrical signals from your pacemaker cells. At this stage, Your heart stops beating because the electricity interferes with these electrical signals. Death is very likely.
200mA: You will start getting 2nd grade internal burns. Death is very likely
300mA: Breathing stops altogether. Death is certain.
900mA: You will get severe internal an external burns. Death is certain.
1A (1000mA): You will start emitting light like a light bulp. There is no way you can survive this amount of current.
If you think that I am trying to scare you from electricity: you are right. Electricity is A DANGEROUS THING! You should always try to work without any voltage or a voltage lower than 50V. If you can not do this, please be very VERY careful! Do not touch any kind of metal, try to isolate yourself from the ground with rubber shoes (rubber doesn't conduct), and make sure you are completely dry.
I will share an experience I've had myself: I got shocked once by 230V. I think about 10mA was flowing through me, cause I couldn't let go. Nothing bad happened, because the GFCI tripped. Which brings me to the next subject: there are a lot more factors to electrocution. They include, but are not limited to:
- The path of the electricity through your body
- The frequency (Only applies to alternating current)
- The duration of the electrocution
- Your own personal electric resistance (Like with fingerprints, this tends to differ from person to person).
This is the end of part 2 guys. Feedback, questions, suggestions? Feel free to comment your thoughts below or PM me. We covered a lot in this article. In the next part, we will talk about Ohm's law and the amount of energy, as well as other things.