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Understanding Electricity

Basic Electrical Definitions

Electricity is the flow of electrical energy through some conductive material. Electronics refers to using changing electrical properties to convey information. Electronic sensors convert some other form of energy (light, heat, sound pressure, etc.) into electrical energy so that we can interpret what’s going on electronically. For example, a microphone changes sound pressure waves in the air to a changing electrical voltage. By amplifying and reading that electrical signal, we can interpret what the sound was that caused it. This process of changing one energy into another is called transduction, and devices that do it are called transducers. Much of the technical work of physical computing is about figuring out what form energy a person is putting out, and what kind of transducer you can buy or build to read that energy. In order to do that, though, it’s necessary to understand a few things about electricity. We’ll start with a few terms we’ll use to refer to electrical properties and components. After that, we’ll talk about the important relationships between some of these terms.

Current is a measure of the magnitude of the flow of electrons in a circuit. It is measured in Amperes, or Amps. Many people explain electrical flow by using water flow as an analogy. Following that analogy, current would be how much water (or electricity) is flowing past a certain point. The higher the amperage, the more water (or electricity) is flowing.

Voltage is a measure of the electrical energy of a circuit. It is measured in Volts. In the water analogy, voltage would be the water pressure. Think of a geyser as high voltage, and the shower of a low-rent apartment on the fifth floor of a tenement building as low voltage (unless you’re one of those lucky people with good water pressure!).