A Geek Girl's Guide to Electronics and the Internet of Things

Introduction

Welcome to the world of electronics! This is an exciting place to be, and I'm so glad that you've decided to join me in this journey. IoT and electronics are inseparable, as you'll soon see. We'll start with learning about electronic components and creating some useful circuits. In addition to traditional electronic circuits on breadboards, many chapters have circuits that use the programming power of an Arduino board. Finally we'll be connecting your circuits to the Internet so you can control them from anywhere. This book starts small and helps you grow in knowledge as it progresses and encourages you to reach even further. My true hope is that it will get you excited about working with electronics, regardless of whether it's a hobby or a new career, and that it will give you confidence to do whatever it is that makes your heart sing, no matter who or where you are in life.

I'm here to tell you that virtually everyone can do electronics, you included. Although this is a male-dominated field, I encourage you not to let that deter you from getting into the game. If you're female or any other non-traditional geek, follow your passion like I did. Like me, you may be the only woman in the room, but that's perfectly fine. It's an exciting and dynamic career field, and if you're different from the stereotypical electronics geek in some way, that's great! You bring a different perspective, which makes you that much more valuable.

Who Will Benefit Most from This Book

This book is intended for beginners, or those with some basic electronics knowledge who want to fill in those knowledge gaps with tidbits of information that can make all the difference. You'll start with the basics and progress to more interesting (difficult) projects as you go along. This book contains more than 35 Try This projects where you can see how things work and solidify what you're learning. Some of the projects include the following:

Creating a super-bright camping light using LEDs

Building a laser trip alarm

Making paper and clay electronics for kids

Creating light-activated circuits

Constructing an Arduino wattmeter

Connecting your projects to the Internet

You'll learn some science behind how things work so the components and connections will make sense, and you'll learn how to avoid some of the pitfalls of circuit building. For example, after studying the material in this book, you'll know why you need a flyback diode for a motor (and understand what one is), instead of having to figure it out when the circuit fails and you're on your third set of components. However, I expect there may be some of that in your future, too, as you take your own ideas and build them into new and interesting circuits. Mistakes are part of the learning process. That's the fun of experimenting! You will create prototype circuits on breadboards, and if you're happy with the result, you can solder them onto something more permanent because you'll know how to do that, too.

Sourcing Parts and Supplemental Materials

I wouldn't want to teach you to fly and then leave you on your own, so throughout the book I've included some of my favorite places to find information and components.

My website, cliffjumpertek.com, also has additional reference materials, tutorials, and videos of the book's projects to help with your journey, should you need it.

Special Features

TIP Throughout the book, you'll find tips that will provide you with supplemental information, usually to make something easier so you don't have to learn from trial and error.

WARNING Included in this book are warnings—please take these seriously! Make sure you read all of these because they have information to protect you or others from injury and/or your project from damage.

NOTE Notes are supplemental material or interesting tidbits of information.

Time to turn the page and get started on your future in electronics! I'll see you there.

What Does This Book Cover?

This book is designed to provide you with a foundation of knowledge in electronics, IoT, and the Arduino environment. Its multitude of projects are the springboard to a deeper understanding and ever more challenging projects.

Chapter 1: IoT and ElectronicsThe book starts with an explanation of how electronic circuit boards fit into the world of IoT. The components of an IoT system are explained, showing how IoT starts with electronic sensors and then interfaces with computers and communication systems. It also notes some of the challenges in developing and using IoT systems, as well as where IoT may be headed in the future.

Chapter 2: Electricity: Its Good and Bad Behavior Understanding how electricity behaves will help you to determine why circuits are or are not working. This chapter delves into the science behind electricity. It also explains electricity's characteristics and the relationship between those electrical characteristics. You'll learn how to build a simple circuit and then how to create a circuit on a breadboard, which is the foundation for most of the circuits created in the rest of the book.

Chapter 3: Symbols and Diagrams The field of electronics uses symbols to represent components when communicating information. This chapter teaches the basic symbology used and how to create a breadboard circuit using a schematic as a guide.

Chapter 4: Introduction to the Arduino Uno The Arduino is a popular platform for creating IoT implementations. In this chapter, you'll learn the form and function of the Arduino Uno and its programming platform. You'll also learn about analog and digital signals and the role of binary, all while building projects.

Chapter 5: Dim the Lights This chapter gets its name from one of the eight labs included in it; however, it's more about measuring electricity. You'll learn to use a multimeter and create a voltmeter, ohmmeter, and ammeter using an Arduino board. There's also a great project for creating a camp lamp, and it finishes with a lesson on soldering, perfboards, and shrink tubing, so you'll know how to put those projects together on a more permanent basis.

Chapter 6: Feel the Power Power is another characteristic of an electrical circuit and is explained in this chapter. You'll learn the relationship between Ohm's law and Watt's law as well as power from batteries, power ratings of resistors, and ways to measure circuit power. You'll also learn how to use an LCD screen with an Arduino board.

Chapter 7: Series and Parallel Circuits Electricity behaves differently depending on the path that it takes through a circuit. This chapter explains the implications of letting it take those different paths. You'll also learn about the effect of wire size and composition. In the spirit of full disclosure, this chapter involves math.

Chapter 8: Diodes: The One-Way Street Sign This is the first of several chapters about specific electronic components. You'll learn about diode construction and why diodes behave as they do, along with some common uses for diodes. The projects show you how to work with seven-segment LEDs and bar LEDs.

Chapter 9: Transistors You may know that transistors are the foundation of our modern computer processors, but they can do so much more. This chapter explains different types of transistors and their uses while giving you some practice working with them.

Chapter 10: Capacitors Another powerhouse when it comes to computer circuits is the lowly capacitor. They're found everywhere and sometimes taken for granted. This chapter teaches you the characteristics of capacitors and gives you some experience putting them to work.

Chapter 11: The Magic of Magnetism Magnetism and electricity are like two sides of a coin. This chapter examines that relationship and how magnetism is put to serious work. You'll also learn about relays, which are a component of many industrial electronic circuits.

Chapter 12: Electricity's Changing Forms Working with electricity is even more fun when you can change it into light and heat and sound, or vice versa. This chapter shows you several ways to do just that, along with the science behind the changes.

Chapter 13: Integrated Circuits and Digital Logic Integrated circuits make our work easier by having an entire circuit on a chip the size of your thumbnail, or even smaller, while digital logic chips can be the decision-makers on our circuits. This chapter explores both and introduces the oscilloscope, which lets you see in real time what is happening electrically in a circuit.

Chapter 14: Pulse Width Modulation Pulse width modulation (PWM) enables a digital signal to control an analog device, such as a motor. In this chapter, you'll build a PWM circuit on a breadboard and then learn how to accomplish the same magic using an Arduino board.

Chapter 15: Sources of Electricity Sources of electricity are touched upon in other chapters, but this one brings all the pieces together in one place. Here you can practice making some electrical current of your own and build an Arduino circuit to monitor the output of a photovoltaic cell.

Chapter 16: Transformers and Power Distribution Transformers are used to change the electrical properties of a circuit and play a big role in power supplies and power distribution. This chapter examines the types and roles of transformers. It also explains how they accomplish changing electrical properties and gives you some experience working with one.

Chapter 17: Inverters and Rectifiers Many times a circuit needs to be converted from DC to AC or AC to DC. The devices that perform that task are called inverters and rectifiers, respectively. In this chapter, you'll learn how both work and how to filter circuits for a more desirable and consistent output. You'll even build a small variable power supply.

Chapter 18: Radio Waves and Tuned Circuits Radio waves are the communication vehicles of our cell phone networks, local area networks, and free music stations. Their use grows every day, so knowing how they work is important whether you're working with computers or IoT devices. This chapter explains AM and FM and introduces working with an Arduino shield to create a radio.

Chapter 19: Connecting Your Circuits to the Cloud Being able to control devices remotely is an important aspect of many IoT implementations. This chapter teaches you how to do just that using a Wi-Fi enabled Arduino board and the Arduino IoT cloud.

Chapter 20: Just for Fun While working with electronics is always fun, most of the time electronic circuits are created for serious work. This chapter explores some of the not-so-serious uses of electricity. If you're the least bit creative, and I'm sure you are, then this chapter is for you!

Part I

IoT and Electricity Basics

In This Part

Chapter 1: IoT and Electronics

Chapter 2: Electricity: Its Good and Bad Behavior

Chapter 3: Symbols and Diagrams

Chapter 4: Introduction to the Arduino Uno

Chapter 5: Dim the Lights

Chapter 6: Feel the Power

Chapter 7: Series and Parallel Circuits

CHAPTER 1

IoT and Electronics

Toto, I have a feeling we're not in Kansas anymore.

—Dorothy, The Wizard of Oz

Sci-fi movies and shows have always been my obsession. As a child, I would watch in awe when reruns of The Jetsons showed people talking on video phones, the almost-human robot maid, and sidewalks that moved. Then there were the Star Trek reruns where characters walked around with communicators that allowed them to talk to anyone just by tapping them. Later, Star Wars had language translators that would automatically translate into any other language … rather like what Google Translator does now.

Forty or fifty years ago, many devices and capabilities that are commonplace now were considered ridiculous, impossible, or mere fantasy. Were these movies and TV shows predictions of the future, or did they help to shape the future by putting these notions of impossible devices into someone's mind to start working on? Either way, many of those devices exist now for us in some form or another. Even 20 years ago, most people still depended on their home phones for communication. Do you know anyone who still has a landline at home? They are few and far between.

The Electronics Technicians Association was founded in 1978 as the electronics industry was beginning to grow slowly. Now, it's growing by leaps and bounds on a daily basis. It's astonishing how far electronics have come in such a relatively short time when compared to human existence, and it's even more incredible when we ponder how far we will be 50 years from now. Many of the technological advances of the future will be here due to artificial intelligence, machine learning, and the myriad of sensors starting to cover our world. The world is about to take another leap forward, and if you want to be part of that journey, learning electronics is the place to start. As so many maps show us … You Are Here.

IoT in a Nutshell

What is IoT? As you may know, IoT stands for Internet of Things. IoT refers to a vast array of connected devices that gather and transmit data over interconnected networks with or without human intervention, sometimes even responding to the captured data automatically as machines talk to machines and learn from each other. (When IoT involves manufacturing processes, it is often called industrial IoT [IIoT].) IoT can include data gathered by proximity sensors on your car's front that detect deer in the roadway and signal your brakes to immediately slow down the car without you doing anything. It also includes when moisture levels (or lack thereof) are transmitted from a field to that field's watering system, signaling to turn on the irrigation system without a human lifting a finger. Even a dog's GPS-enabled location device is part of an IoT system, as is the Tile that I press to locate my often-misplaced car keys.

Other systems considered part of IoT are smart cities, smart grids, smart homes, smart watches, and manufacturing machines talking to and learning from each other. Smart devices are used in hospitals, schools, retail, and nearly any other service or business you can think of. Last year, I attended a virtual meeting with someone from a major networking device company. He was speaking from his office about power over Ethernet and how the interconnected devices controlling heat, lighting, air quality, etc., all ran automatically in the high-rise office building he was in. I noticed a model of a pig on the credenza behind him and asked about it. Yes, it was a pig wearing an IoT collar.

What does this have to do with learning electronics? Everything! Electronic sensors and circuits are the beating heart of an IoT system.

Parts of an IoT System

What comprises an IoT system changes depending on who you ask, but regardless of what particular twist an industry or company may put on it, certain things must be there. For an overview of an IoT system, see Figure 1.1.

Devices

What is an IoT device? IoT devices include sensors, circuits, software, actuators (things that do something, such as switch from one state to another), and microprocessors, all rolled into a neat little package. These devices also need a way to communicate and send data to a place where it will be processed, manipulated, and action taken based on the data, or they need to be able to communicate to receive instructions based on the data that was gathered by some other device. Therefore, an IoT device can be on either the sending end or the receiving end, or possibly both.

Figure 1.1: An IoT system

Take, for example, a smart home with a remote-controlled thermostat, which has a few layers of things going on. First, the thermostat is a device. It has a sensor that measures the temperature and sends that information to a circuit board with a microprocessor where the reading is converted into data, which is manipulated. If certain conditions within the software program are met, the microprocessor sends a command to another component, telling it to turn the furnace either off or on. This example is machine to machine but involves sensors, circuits, software, microprocessors, communication, and actuators.

Another function of this device would be the ability to access the device from a cell phone via the Internet and Wi-Fi to tell the device to turn up the heat before the user gets home. This example involves a user interface, which is part of the entire user experience, but here we have the cell phone acting as a device and the thermostat acting as another device, communicating via the Internet.

Sensors

The first part of any IoT system is a device that senses something physical, whether a particular condition or event. It could be a fiber optic cable in a building's concrete that picks up a pressure change, or it could be a proximity sensor, heat sensor, humidity sensor, optical sensor (ambient light, IR, UV), gas sensor, position sensor, magnetic sensor, motion sensor (accelerometer, gyroscope), color sensor (light again), or touch sensor (pressure). A search for sensors on an electronics components site at the time of this writing yielded tens of thousands of results.

As mentioned in the preceding section, a sensor receives some form of raw data and passes it on to a circuit and most likely a microprocessor, where the data received is interpreted. Take, for example, a temperature. The sensor doesn't send temperature to the circuit. Instead, a change in the temperature causes a rise or fall in either current or voltage through the device, which is passed to a circuit where it is read and interpreted according to instructions, known as software, controlling what the microprocessor tells the circuit to do. In future chapters, you'll learn how to work with some of these sensors and what the technology is that drives them.

Choosing the right sensor is an important first step, and several characteristics need to be considered.

What's being measured: Temperature, light, pressure, etc.

Electrical: Current, voltage, and power limitations.

Physical: How much pressure, heat, light, etc., can it endure and remain viable?

Accuracy: How far might it vary from the actual measurement?

Sensitivity: How much does the input need to change before the output changes?

Reliability: What is the track record of this sensor? When does it stop being accurate? How often does it break down?

Range: What are the minimum and maximum values that can be measured?

Circuits, Software, and Microprocessors

Once the right sensor is found, the circuitry and software can be designed to interpret the information that is provided by the sensor. A myriad of choices exists for all of these. A microprocessor can be a single chip designed to perform logic or a microprocessor platform, such as an Arduino device. The choice of processor may determine the choice of software that is used.

Communication

Because the I in IoT stands for Internet, the assumption can be made that the device is expected to be interconnected in some way either through a local area network (LAN) or through the Internet. However, different levels and aspects of communication may be used by IoT devices.

Levels

A device may communicate with other devices, such as a moisture sensor in a field that triggers a watering system to work, or devices in a factory assembly line that communicate with other devices to either slow down or speed up the processes based on conditions. This is machine-to-machine communication. Systems like these may even use machine learning, which is a process where computers use algorithms to look for related data and learn, changing their programming based on data without human intervention. Machine learning is far too complicated to explain here but definitely an emerging technology worth paying attention to.

In the automatic watering system example, the devices may be connected only to a LAN, but most likely they will be gathering data and sending it, via one or more protocols and networks, to a place where it is processed.

Protocols and Standards

Protocols are essentially rules for communication, and they are the topic of much learning and discussion in the computer world. Standards typically define how a network is built and what protocols are used on it. Networking standards are needed to ensure that different devices, possibly from different vendors or manufacturers, are all able to communicate effectively. Knowing what type of communication is needed and used by each part of an IoT system is an important consideration. Any of the following standards might be part of an IoT system:

Ethernet: Wired LAN networking standard

Bluetooth: Short-range wireless, usually connecting mobile devices

Wi-Fi: Wireless networking standard allowing wireless networks to connect to a wired system or each other

Cellular: For longer-range wireless connectivity via the cellular system

Each of these standards may have multiple protocols that are used with that particular standard, and any of them may allow a device to connect to the Internet. Often more than one will be used. In the case of the smart thermostat, it may use Wi-Fi to connect to a local LAN using Ethernet, which is connected to the Internet via some other method, such as a cable modem, fiber optics, or satellite. The remote user may be connecting their cell phone to the thermostat via Wi-Fi or the cellular network. All of these standards need to work in harmony for successful communications across an IoT system.

Data Analytics and Management

Data analytics is the growing field of sorting and analyzing raw data to derive meaningful and actionable information from it. It is the stuff of algorithms and perhaps insight gained from the experience of working with data. Four basic types of data analysis exist.

Descriptive

Diagnostic

Predictive

Prescriptive

Descriptive analytics identifies what has happened based on data. It is often based on key performance indicators (KPIs). For example, did sales go up or down and by how much or what percentage? Did the field have to be watered more often or less often?

Diagnostic analytics attempts to explain why the changes occurred. It can look at data outliers and what was occurring when the change in data occurred.

Once the what and why are known, predictive data analysis models can be built to anticipate problems before they happen or identify future trends.

Finally, prescriptive data analysis gives the user a course of action to take to avoid the problems identified in predictive models or to take full advantage of what's around the corner.

Data is more valuable than the hardware and software used to mine it from various sources, so managing that data is a primary concern for any business. The field of data management is concerned with collecting data, maintaining its physical security, securing the privacy of any personally identifiable information (PII), and preserving that data in a cost-effective and efficient manner. Data analytics is part of data management, and the way this data is used can cause a business to flourish or fail.

The User Experience

The user experience refers to every place that the user and the IoT system come into contact with each other. If, for example, an employee is tasked with identifying a problem quickly and accurately, then the interface that the employee uses needs to have the right information in an application that is easy to use, and it needs to be updated in a timely manner.

Depending on the situation or business, the user experience can also include interacting with customer service or other personnel, how easy the phone system is to use, etc.

Challenges in Implementing IoT

Implementing technology is not without challenges, particularly in an IoT system. One of the biggest challenges for remote IoT devices is power. Running electrical wires is not always practical, and batteries have a limit to their capacity, so creating a system that runs on as little power as possible, or perhaps renewables like solar power, is a significant hurdle to overcome in developing an IoT solution.

Another major concern is the security and ownership of data. If data is stored by a provider, who owns and has access to the data? What encryption will be used to transmit the data from where it's gathered to where it's used? These are questions that any businessperson would want to know before implementing a system. Determining the right data to gather is probably the first question to answer, because measuring the wrong facts won't help a business make the right decisions.

Perhaps the biggest challenge of all is cohesiveness. If a system is cohesive, then it works together smoothly, which can be a problem when so many different systems are involved. Beginning with the sensors that detect data, through the circuitry and networks that transfer and store the data, then send the data to a user's interface on a device such as a phone or computer, and back again as the user responds through a local network to the web and then to the actuator; during this process, there needs to be a seamless way to transmit and manipulate the data. With so many protocols and systems involved, that can be difficult indeed. Developing a system needs to start with a bird's-eye view of the major parts, working down to the component level to ensure that all of the system's parts work together to move data around smoothly.

IoT into the Future

IoT and IIoT will not be going away in the foreseeable future. In fact, they will continue to grow as processes and machines get smarter and people find more uses for IoT. What may have started as a curiosity, with devices that were more fun than function in the hands of a few hackers, is now a major industry and will be causing paradigm shifts in virtually all industries and businesses.

Devices and sensors will continue to get smaller, get less expensive, and work better. We will learn how to better harvest the data from IoT devices and put them to more and more uses. Already billions of IoT devices are being used, and the number increases exponentially as every day forward-thinking inventors and electronics enthusiasts devise more uses for the technology. Where will you fit into this growing industry? Perhaps the best place to start is with a basic understanding of electronics, and to that end, read on.

CHAPTER 2

Electricity: Its Good and Bad Behavior

Never trust an atom. They make up everything.

Unknown

You probably already have an idea of how electricity behaves. If you turn on a light switch, electricity is converted to light. It makes motors run and can be created by a generator to charge our cell phones when the power is out. You also know that it's a bad idea to stand outside in a lightning storm because it's likely also raining, and if you're wet and the tallest thing around, you're practically inviting lightning to strike you. Electricity can keep us alive if it's powering our heart, and it can kill us if we don't respect it. What you may not understand is why electricity behaves the way it does, which is what this chapter is about. If you're going to be the next Bill Gates or Steve Jobs and invent something that will alter life as we know it, you'll need to start with a basic understanding of how and why electricity behaves the way it does.

First, a little static electricity lab.

Try This: Creating Some Static

This lab is just for fun. Most grade-school kids have rubbed a balloon on their head or combed their hair with a plastic comb and seen the magic that is static electricity. What happens is that the energy of friction pulls electrons from the atoms of the hair onto the comb or balloon, giving it a negative charge and the hair a positive charge. The negatively charged balloon attracts the more positively charged hair. (Opposites attract.) If two balloons are negatively charged, they will push away from each other. (Like charges repel.) You can also do other fun things with static. The following sections contain a few for your amusement.

For these projects, you need the following materials:

Fur, wool cloth, or hair (a source of electrons)

PVC pipe about 2′ long

Styrofoam plates

Water faucet

Balloon

Fluorescent tube

Water glass or glass vase

Styrofoam ball

Aluminum foil

String

Levitate a Styrofoam Plate

Rub a Styrofoam plate with a wool cloth to charge it and then set it on a flat surface.

Rub a second Styrofoam plate to charge it as well.

Try to put the two plates together. If they push away from each other, you know they're both negatively charged. Now, put your hand a few inches above the plate that's on the table and try to place the other plate on top of the first one. It should float up to your neutral (no charge) hand. It is being pulled by your hand and pushed by the other plate.

Bend Water

Negatively charge the PVC pipe by rubbing it with the fur or wool cloth.

Turn a water faucet on so that it is running a small steady stream.

Move the charged PVC pipe near but not touching the water. You should see the water bend toward the more negatively charged PVC pipe (Figure 2.1).

Creating Light with Static

Negatively charge the balloon by rubbing it with the wool cloth, hair, or fur.

Enter a darkened room.

Touch the balloon to the two electrodes sticking out of the fluorescent tube. The tube completes the circuit and inside the tube the electrons excite the gasses and cause the glow.

Figure 2.1: Bending water

The static electricity generated this way will have enough voltage but not enough current to light a light-emitting diode (LED), which we'll talk about later. It does have enough voltage to excite the electrons of the gasses in the fluorescent tube. The process is similar to someone walking across a carpet and then touching a metal doorknob. They may get quite a shock when the negatively charged electrons jump to the more positively charged doorknob. The electrons move quickly and may cause sound or a flash of light and be thousands of volts but not a lot of current. Current and voltage will be explained soon.

Magically Move a Styrofoam Ball

Wrap a small Styrofoam ball with aluminum foil.

Tie a string around the ball.

Tape the end of the string to the inside bottom of the water glass or glass vase, making sure that the ball will hang freely when the glass is turned upside down.

Turn the glass upside down.

Charge the PVC pipe and bring it toward the glass. The ball is attracted to the negatively charged PVC pipe.

While these were fun demonstrations of static electricity and the law of charges (like charges repel each other, opposite charges attract), static electricity does have some serious industrial uses. Static electricity is responsible for transporting toner inside a printer from the negative toner container to the more positive (but still negative) drum and finally onto the positively charged paper. Static is also used in some pollution control systems where particles are charged and then attracted to plates with the opposite charge, reducing pollution. Static is also used in applying paint to cars. What causes those charges? Read on.

Electricity at an Atomic Level

What is electricity? To understand it, you need to look at atomic structure. Figure 2.2 shows a two-dimensional drawing of a three-dimensional object, an atom. To be specific, it is the structure of a gold atom. Atoms are the building blocks of everything, including human beings. At the center of the atom is the nucleus, which contains particles called protons and neutrons. Orbiting around the nucleus is a cloud of particles called electrons. Electrons are located in orbitals and shells at various distances from the nucleus in the center depending on the energy they exhibit at the moment. A gold atom has 79 protons, 79 electrons, and 118 neutrons.

Figure 2.2: Atomic structure of gold

Matter that is made of only one type of atom is called an element. These elements and the information about each can be found on the periodic table of elements (Figure 2.3). While there are 94 naturally occurring elements, more have been created by humans. Each element is assigned an atomic number, which is equal to the number of protons in the nucleus of the atom, so our gold atom's atomic number is 79.

Protons have a positive charge, neutrons have no charge, and electrons have a negative charge. Atoms seek to be in balance, so when they are at a ground state, atoms always have the same number of protons and electrons, making the atom have a net neutral (no) charge. When an atom is acted upon by some outside force such as friction, it can lose or gain electrons. This process of losing and gaining electrons is called ionization. Because electrons are negative, if the atom loses an electron, it becomes a positive ion. It will have more positively charged particles (protons) than negatively charged particles (electrons) and therefore a net positive charge. If an atom gains an electron, it becomes a negative ion because there are more negatively charged particles (electrons) than positively charged particles (protons).

Figure 2.3: Excerpt from the periodic table of elements

NOTE The designations of positive and negative were chosen by Benjamin Franklin as a way to explain his observations of electrical behavior.

The law of charges tells us that opposites attract, so the positively charged protons are always pulling on (attracting) the negatively charged electrons. When ionization occurs, the electrons the atom loses (or gains) will be located in the outermost shell, which is called the valence shell. If an electron in a lower shell is acted upon by some outside energy, such as heat or light, it can jump to a higher shell. When it loses its energy, it falls back down toward the nucleus. Only a certain number of electrons can exist in a given shell, but right now we don't need to explore that any further.

What does this have to do with electricity? Everything! What we know as electricity is the movement of those electrons from atom to atom in the same general direction, as they're trying to balance atoms in a chain reaction.

Conductors and Insulators

Certain elements will easily give up their valence electrons. We call those elements good conductors. Examples of good conductors are gold, aluminum, copper, silver, and mercury. Each of these conductors has characteristics that make them better than the others in certain situations. For example, silver is the best conductor, but gold is often used for connections on computer boards because of its tendency to avoid corrosion. Mercury is a liquid that has been used in devices such as thermostats, thermometers, and motion switches, and for measuring pressure. However, because it has been identified as a pollutant, the electrical and electronics industries have been working to replace mercury in electrical and electronic devices. Despite their efforts, many devices containing mercury still exist. Copper is used in household wiring because it is less expensive. Aluminum is used in buildings, too, but it is less conductive than copper and weighs much less, so it is useful where a lighter-weight