Electrons, Protons and Neutrons: Inside an Atom
Learn where electrons, protons and neutrons are found, what determines an element, and how moving charge relates to electricity. Video and explanation by Erika Barker.
From the electron to the app
Videos.
I wanted to understand how a computer works, starting with the electricity that makes it possible. These lessons follow that thread through circuits, components, binary, processors and connected devices. Start at the beginning or jump to the question that interests you.
Charge & circuits
Part 1
What Is Electricity? Charge and Current Explained
Why a balloon attracts your hair, what electric charge means, and how static electricity differs from current. A video lesson and explanation by Erika Barker.
Conductors and Insulators: Why Rubber Resists Current
Some materials let electric charge move easily, while others strongly resist that movement. Metals have mobile electrons, whereas an ordinary insulator has very few charges available to carry current under normal conditions. That distinction helps explain why wires use a conducting core and an insulating covering.
How Electrical Circuits Work: Source, Path and Load
A simple circuit connects an energy source to a load through a complete electrical path. The load might be a lamp, a motor or another device that turns electrical energy into something useful. Voltage, current and resistance describe what happens in that path, while power tells us how quickly energy is transferred.
Volts vs Amps: What Is the Difference?
Voltage and current describe different parts of an electrical circuit. Voltage tells us how much energy is available per unit charge, while current tells us how much charge passes a point each second. Thinking about water pressure and flow gives us a starting point for understanding how a circuit supplies power.
Ohm's Law Explained: Voltage, Current and Resistance
How voltage, current and resistance connect through Ohm's law, with a worked 120 V and 10 ohm example. Watch Erika Barker's lesson and read the transcript.
Electrical Power Explained: Watts, Volts and Amps
Electrical power tells us how quickly energy is transferred. In a DC circuit, multiplying voltage by current gives power in watts. Combining that relationship with Ohm’s law helps explain both useful power at a load and heat dissipated in resistance.
AC vs DC: Alternating and Direct Current Explained
Alternating current reverses direction, while direct current keeps flowing in one direction. Homes commonly receive AC, and many electronic devices convert that supply into DC internally. Diodes help with that conversion by allowing current to pass much more easily in one direction than the other.
What Is Frequency? Hertz, Waves and AC Electricity
Frequency describes how often a repeating event completes a cycle. One hertz means one cycle per second, whether we are talking about a wave, an electrical signal or a clock. That idea connects sound and alternating current to the timing signals used in digital electronics.
Electromagnetism Explained: Electricity and Magnetism
Electricity and magnetism are connected parts of the same physical interaction. A current creates a magnetic field, and changing magnetic flux can produce an induced voltage. Those relationships are behind the motors, generators and transformers that turn electrical ideas into useful machines.
Components & switches
Part 2
How Resistors Work: Resistance and Heat
A resistor gives us a way to control current in a circuit. For the same applied voltage, a larger resistance allows less current to flow and turns electrical energy into heat. That makes resistors useful for setting operating conditions and protecting components from excessive current.
How Potentiometers Work: The Electronics Behind a Volume Knob
A potentiometer turns a physical movement into an adjustable electrical value. Its wiper slides along a resistive track, changing the resistance between the wiper and either end. Connect the ends across a supply and the wiper gives you an adjustable fraction of that voltage.
Batteries vs Capacitors: How They Store Energy
Batteries and capacitors both store energy, but they store it in different ways. A battery uses chemical reactions, while an ordinary capacitor stores energy in an electric field between separated charges. That difference makes capacitors useful for quick bursts and filtering, while batteries commonly supply energy over longer periods.
How Capacitors Work: Electric Fields and Quick Energy Storage
A capacitor stores energy in an electric field between separated charges. Its conductive surfaces are separated by an insulating dielectric, which lets it hold that separation without a direct conducting path between the plates. A circuit can use that stored energy for a brief burst, or use the capacitor to help filter changing signals.
How Inductors Work: Coils, Magnetic Fields and Stored Energy
An inductor stores energy in a magnetic field when current flows through it. It opposes changes in that current, which is why a coil can produce a voltage spike when a circuit switches off. That behavior makes inductors useful in power supplies, filters and magnetic devices.
How Diodes Work: Rectifiers and One-Way Current
A diode acts roughly like a one-way valve for electrical current. That makes it useful for rectifying AC, steering signals and protecting parts of a circuit when the right device is selected. Different diode types also let us regulate voltage or produce light.
How Transistors Work: Electronic Switches and Amplifiers
A transistor lets one electrical signal control another current. It can act as a switch or operate as an amplifier, depending on how the circuit uses it. Put many transistors together and those small controlled actions become the logic and signal processing inside modern devices.
How Amplifiers Work: From Microphones to Camera Sensors
An amplifier lets a small signal control a stronger output. The extra energy comes from a power supply, not from creating energy inside the input signal. That is how a microphone signal can help drive a speaker or a small sensor signal can become easier to process.
Buttons vs Switches: How They Control a Circuit
A switch controls a circuit by making or breaking an electrical connection. A common push button makes that connection only while you hold it, while a maintained switch stays where you put it. Those simple actions give a device a way to respond when you press, flip or release a control.
How Breadboards Work: Prototyping Circuits Without Solder
A breadboard lets you connect components without soldering them together. Metal contacts beneath the holes join selected rows and power rails, so where you place a wire matters. You can move parts around, test an idea and then transfer a working circuit to a permanent board.
How Voltage Dividers Work: Resistors and Output Voltage
A voltage divider uses resistors to produce a fraction of an input voltage. The output comes from the junction between the resistors, and their relative values determine the unloaded ratio. Connecting a load changes the circuit, which is why a divider is useful for many measurements but is not a general power regulator.
Bits & processors
Part 3
How Binary Code Works: 0s, 1s, Numbers and Text
How do computers use 0s and 1s? Learn binary numbers, bits, ASCII and text encoding with Erika Barker’s video, worked examples and transcript.
Boolean Logic Explained: AND, OR and NOT Gates
A computer can turn simple true-or-false decisions into much more complicated behavior. AND requires both inputs to be true, OR requires at least one and NOT reverses the input. Combining those operations gives us the logic circuits behind processors, memory and everyday digital devices.
How Billions of Transistors Fit Inside a CPU
Chip manufacturing repeats extremely small patterns across a silicon wafer. Lithography helps define those patterns, and many fabrication steps build transistors and the connections between them layer by layer. The wafer is then cut into individual dies that can be packaged and connected to the rest of a device.
How Microcontrollers Work: Processor, Memory and Input-Output
A microcontroller puts a processor, memory and input and output connections on one chip. Its program reads information from the outside world and decides what the device should do next. That small package is what lets a washing machine, a traffic light or a robot respond to what is happening around it.
What Is CISC? CPU Instructions and Computing History
An instruction set defines the operations software can ask a processor to perform. CISC designs include instructions that can express relatively complex work, and a processor may implement some of them through smaller internal operations or microcode. The instruction seen by a programmer and the work performed inside the chip are related, but they are not the same layer.
GPUs vs CPUs for AI: Parallel Computing Explained
CPUs and GPUs are designed around different kinds of work. A CPU handles a broad mix of tasks, while a GPU can apply similar operations to many pieces of data at once. That makes GPUs useful for many deep-learning calculations, including matrix multiplication, when the workload is large enough to benefit.
Software & networks
Part 4
A Short History of Linux, GNU and the Linux Kernel
Linux is the kernel that manages core interactions between software and hardware. Many complete operating systems combine it with GNU tools and other software developed by a wider community. That distinction helps explain how one kernel became the foundation for many different systems.
How TCP and IP Work: Packets and the Internet
Internet communication relies on several protocols working together. IP helps packets reach their destination, while TCP can provide an ordered, reliable stream of data between applications. The receiving application then decides what those bytes mean, whether they represent a page, a message or part of a video.
What Is Oblivious DNS over HTTPS? Internet Privacy Explained
DNS helps a browser find the address associated with a website name. Oblivious DNS over HTTPS adds a proxy and encryption so that the proxy and resolver each see only part of the lookup. That separation improves privacy when the services do not combine their knowledge, but it does not make every part of browsing anonymous.
What Is Edge Computing? Processing Data Closer to Its Source
Edge computing moves some processing closer to where data is created. A device can handle a local task before sending information to a distant server, which can reduce delay and network traffic. The useful question is which work belongs nearby and which work still benefits from the cloud.
What Is the Internet of Things? Connected Devices and Sensors
The Internet of Things connects physical devices so they can collect information, exchange it and act on it. Sensors give those systems a way to notice temperature, movement, sound and other conditions in the real world. The useful result depends on what the system does with that information, from adjusting a room to helping manage a factory.
What Is TinyML? Machine Learning on Small Devices
TinyML brings small machine-learning models to devices with tight memory and power limits. A local model can detect a pattern, such as a wake word, without sending every sample to a distant server. The device can then act on that result or send selected information onward when the application needs it.