What Is Electricity?
Electricity is one of the primary forms of energy. Although we cannot see electricity, we know it is present when we see light from light bulbs, hear a stereo, feel heat from a space heater, or use a computer. Here we look at what electricity is and how it powers these everyday activities.
Electricity
All forms of matter (for example, wood, plastic, metal, glass, air) are composed of tiny particles called atoms with a balance of positive and negative electrical charges. The nucleus of an atom is composed of positively charged protons as well as neutrons, which have no electrical charge. Surrounding the nucleus are negatively charged electrons which generally balance the positive charge of the protons.
An atom can gain and lose electrons, but the number of protons and neutrons generally remains constant. It is the gain and loss, or flow, of the electrons that creates an electric current. An electric current flows in a circuit, which is essentially a pathway. A current flows because electrons are moving from one atom to the next in the circuit. A circuit is the means by which we obtain the electricity to power appliances, computers, stereo equipment, etc.
Electric Circuits and Currents
Circuits are typically created using a metal wire or other material that efficiently conducts electricity from a source of elecricity to its end use. An especially visible part of a circuit is the electrical cord that connects an appliance or other machine to a wall socket. The wires in the cord connect through the appliance and complete the electrical circuit when the cord is plugged into the socket.
There are two types of electrical currents: direct and alternating. Direct current (DC) flows steadily in one direction along a circuit. Alternating current (AC) reverses direction at regular intervals. In the U.S. , electrical current that comes out of wall sockets is AC power. DC power is used mainly in low-voltage applications that are not served by utility power, such as laptops, flashlights, and cell phones. Sources of DC power for these devices include batteries, electrochemical cells, and photovoltaic cells.