DC Circuit Components 221

AC

Alternating current. Electricity that reverses direction at regularly recurring intervals of time. AC powers the electric grid.

actuate

To initiate the operation of a machine or device. Control devices may actuate manually or automatically.

alternating current

AC. Electricity that reverses direction at regularly recurring intervals of time. Alternating current powers the electric grid.

anode

The negative electrode in a cell. The anode releases electrons as a cell discharges.

arc faults

A short circuit fault that occurs when an electric arc forms between exposed conductors. Arc faults can produce arc flash.

armature

The component of a generator in which current is induced. The armature usually consists of a series of coils or groups of conductors surrounding a core of iron.

armature windings

A conducting wire wrapped around the armature of a generator. Armature windings can connect in series, parallel, or both.

arsenic

A metallic element used as a doping agent for semiconductors. Arsenic increases the number of electrons in the valence shells of the semiconductor's atoms.

atoms

The smallest distinguishable unit of a material that maintains that material's characteristics. Atoms are made up of protons, neutrons, and electrons.

batteries

A device that uses metals to convert chemical energy into electrical energy. Batteries are the primary source of direct current.

bimetallic strip

A component made of two metals with different expansion temperatures that curls up when exposed to heat. Bimetallic strips are often used to detect temperature in circuit breakers.

brushes

A sliding electrical contact that transfers current between the armature of a DC generator and the external circuit. Brushes contact segments of the commutator, which connect to different armature windings.

button-cell batteries

A small, round battery that provides power for watches and very small devices. Button-cell batteries are primary cell batteries.

carbon

A common nonmetallic element that is very strong and resistant to heat. Carbon is used to form the body of resistors.

cathode

The positive electrode in a cell. The cathode reacts with the anode to release electrical energy.

cell

A single unit of a power source, such as in a battery, solar cell, or fuel cell. A cell can contain two different metals in an electrolyte solution.

ceramics

A hard, brittle material that consists of both metallic and nonmetallic atoms held together by a strong primary bond. Ceramics can have piezoelectric properties.

charged particles

An atom possessing an electric charge. Charged particles can be either positive or negative.

chemical energy

A form of energy created by a reaction between two or more substances. Chemical energy is stored in batteries and fuel cells.

chemical reaction

A process in which one or more substances are changed due to the introduction of another substance. Chemical reactions allow batteries to produce electricity.

circuit

A completely enclosed path for electrical current. Circuits include a source, path, load, and control.

circuit breaker

An overcurrent device with a bimetallic strip that bends and trips a switch to open a circuit. Circuit breakers detect excess current to prevent overheating in a circuit.

commutator

The rotating device that transfers current from the armature of a DC generator to the brushes. The commutator maintains DC even though the polarity of the armature changes as it rotates.

conductivity

A material's ability to act as a medium for conveying electricity. Conductivity depends on a material's atomic structure.

conductors

A material or element that allows free movement of electrons and therefore allows easy flow of electricity. Conductors are typically metals.

contacts

A conductive metal part that opens or closes a circuit by separating from or touching a matching part. Contacts close to allow current to flow and open to prevent it from flowing.

control

A component in a circuit that regulates the flow of electricity. Controls determine when a circuit is energized.

control devices

A component in a circuit that manipulates the flow of electricity. Control devices determine when a circuit is energized.

copper

A highly conductive, reddish-brown metal. Copper is often used for electrical wiring in houses, buildings, and machinery.

corrosion

The process by which a material gradually degrades or wears away. Corrosion typically occurs when a material is exposed to atmosphere, moisture, or other substances.

crystals

A solid material with atoms arranged in a highly organized and repeating structure. Certain crystals produce piezoelectricity.

current

The flow of electricity. Current strength is called amperage and is measured in amperes (A).

DC

Direct current. Electricity that travels in one continuous direction. DC does not reverse the direction of flow.

diameter

The distance from one edge of a circle or circular object to the opposite edge as measured through the center. Diameter describes the width of round and cylindrical objects, such as wires.

diode

A semiconductor device that allows electricity to flow in only one direction. Diodes use polarity to control current flow.

direct current

DC. Electricity that travels in one continuous direction. Direct current does not reverse the direction of flow.

discharges

To release its stored energy. As a battery discharges, electrons move from the anode to the cathode through an external circuit.

doped semiconductor

A semiconductor that has added impurities. Doped semiconductors are more conductive than pure semiconductors because of these impurities.

dry-cell battery

A battery that uses a paste electrolyte. Dry-cell batteries are considered primary cell batteries.

electric shock

The flow of electricity through the body. Electric shock can be fatal.

electric vehicles

EVs. A vehicle that is propelled by an electric motor that draws its power from a battery. Electric vehicles require high-energy, lightweight, rechargeable batteries.

electrical energy

A form of energy created by the movement of electrons. Electrical energy can be converted into light, heat, or motion.

electrochemical series

A list of metals in order from most likely to release electrons to least likely. The electrochemical series, also known as the electromotive series, is used to select metals for use in batteries.

electrode potential

The voltage induced by the electrode and electrolyte. Electrode potential measures the ability of a metal to release electrons or take electrons.

electrodes

A device in an electrical circuit that conducts electricity. Electrodes have a positive or negative charge.

electrolyte

A conductive solution containing an acid, an alkaline, or a salt. The electrolyte in a battery connects the two electrodes.

electromagnets

A magnet that gains an attractive force only when current passes through it. Electromagnets for generators are formed by connecting pole pieces and field windings.

electromotive series

A list of metals in order of from most likely to release electrons to least likely. The electromotive series, also known as the electrochemical series, is used to select metals for use in batteries.

electrons

A negatively charged particle that orbits the center of an atom. Electrons moving between atoms causes the flow of electricity.

EVs

Electric vehicles. A vehicle that is propelled by an electric motor that draws its power from a battery. EVs require high-energy, lightweight, rechargeable batteries.

field windings

A conducting wire that connects the pole pieces in a generator. Field windings energize the pole pieces to create electromagnets that form a magnetic field.

fixed resistors

A device that opposes a specific amount of current flow. A fixed resistor consists of a carbon body with metallic leads.

flux lines

An imaginary line of force that surrounds a magnet. Flux lines form a magnetic field.

frequency

The rate at which movement caused by vibration occurs. Frequency measures the number of oscillations per second in hertz (Hz).

fuel

A material used to produce power or heat. Fuel sources for fuel cells include gas and hydrogen.

fuel cells

A device that uses gas or liquid fuel to convert chemical energy into electrical energy. Fuel cells are potentially very efficient power sources.

fuse

An overcurrent device with a metallic component that melts to open a circuit. Fuses detect excess current to prevent overheating in a circuit.

gauge

A standard of measurement used to indicate the diameter of conducting wire. The gauge of a wire is a number that decreases as diameter increases.

generators

A device that uses magnetic induction to convert mechanical energy into electrical energy. Generators require special components in order to output DC power.

gold

A soft, yellow metal that is highly conductive. Gold is resistant to corrosion and often used as a conductor in electronic devices.

ground

A source of zero electrical potential, such as the earth or another large conducting body. A ground absorbs electrical currents.

hydrogen

A colorless, odorless active gas that is the most abundant element on the planet. Hydrogen is the most common fuel used in fuel cells.

hydrogen fuel cell

A type of fuel cell that uses hydrogen gas as fuel. Hydrogen fuel cells do not produce carbon emissions.

insulation

A material used to prevent the flow of electricity. Insulation is used to cover electrical wires and other conductive components.

insulators

A material or element that exhibits high resistance to electrical current. Insulators include rubber, plastic, and ceramics.

lead

A conductive device within a circuit to which other components can be attached. A lead, also known as a terminal, may have either a negative or positive charge.

load

A component in a circuit that converts electricity into work. Loads include light bulbs, appliances, and motors.

magnetic field

The area in and around a magnet in which a magnetic force exists. Magnetic fields exhibit the powers of attraction and repulsion.

magnetic flux

The force that surrounds a magnet and exhibits the powers of attraction and repulsion. Magnetic flux is described as imaginary lines of force that exit one pole of a magnet and return to the other.

magnetic induction

The use of magnets to produce voltage in a conductor. Magnetic induction occurs whenever a conductor passes through magnetic lines of flux.

mechanical energy

A form of energy created by motion and physical interaction. Mechanical energy can be converted into electrical energy by a generator.

mechanical stress

A force that attempts to deform an object. Mechanical stress causes piezoelectric materials to release an electrical charge.

negative

An electric charge with a surplus of electrons. Negative materials are more likely to release electrons.

operator

The part of a manual control device that is pressed, pulled, or turned by an individual to acuate its contacts. Operators come in a variety of styles and sizes.

oscillator

A device that produces a consistent vibrating signal. Oscillators are used in watches to help keep time.

overcurrent devices

A component that protects circuits from excess current flow to prevent fires. Overcurrent devices include fuses and circuit breakers.

overvoltage

The increase of voltage beyond the accepted range of a circuit. Overvoltage can cause significant damage to components if diodes are not used in the circuit.

oxidize

To release or remove electrons from an atom, an ion, or a molecule. Metals that are more likely to oxidize are often used as the anode in batteries.

path

A conductor that directs electricity in a circuit. Paths are often made of copper wire.

photons

A particle of light energy. Photons are converted into electricity by solar cells.

piezoelectricity

An electrical charge produced by mechanically manipulating certain solid materials. Piezoelectricity can be produced by stretching, compressing, striking, or twisting some crystals and ceramics.

piezotronics

A device with piezoelectric materials that is used in electronics as a sensor that produces voltage. Piezotronics are a semiconductor device.

plastic

A lightweight material that resists corrosion and is easily shaped. Plastic is an insulator.

PN diode

A diode that has one positively charged side and one negatively charged side. The PN diode allows current to flow only from the negative side to the positive side.

polarity

The state of having two oppositely charged poles, one positive and one negative. Polarity determines the direction in which current flows.

pole pieces

A block of metal used in devices such as generators that helps create the magnetic field. Pole pieces connect to field windings and form electromagnets.

positive

An electric charge with a shortage of electrons. Positive materials are less likely to release electrons.

power distribution unit

PDU. The junction box inside an electric vehicle that controls the amount of electricity delivered to various components, such as the electric motor. Power distribution units contain circuit breakers to prevent damage to the battery.

primary cell battery

A battery that cannot be recharged. Primary cell batteries are usually dry-cell.

pure semiconductor

A semiconductor that contains no added impurities. Pure semiconductors are less conductive than doped semiconductors.

quartz

A hard, piezoelectric crystalline mineral. Quartz is made of silica.

rectifiers

A device used in an electrical circuit to convert AC to DC. Rectifiers use diodes to prevent current form flowing in more than one direction.

resistance

The opposition to current flow. Resistance is measured in ohms (Ω).

resistor

A device used to limit current flow in circuits. Resistors can be used to prevent overheating.

rubber

A natural and very elastic polymer that is harvested from the sap of tropical trees. Rubber was once used as insulation for conductors.

secondary cell battery

A rechargeable battery. Secondary cell batteries are usually wet-cell.

semiconductor

A material that restricts electrons but still allows them to flow. Semiconductors, such as silicon, have more electrical conductivity than insulators but less than conductors.

sensors

A device that detects a change in physical stimulus and turns it into a signal that can be measured and recorded. Sensors often convert pressure or light into electrical signals that can be collected as data.

short circuits

An electrical fault that occurs when current takes a shorter, unintended path between two conductors. Short circuits can result from damaged insulation on wires.

silicon

A lustrous, gray, semi-metallic material. Silicon is a semiconductor.

silver

A soft, gray-white metal that has the highest electrical conductivity of all metals. Silver is extremely conductive and often used as a conductor in electronic devices.

solar cells

A device that uses semiconductors to convert light energy into electrical energy. Solar cells, also known as photovoltaic cells, produce DC power.

solid-state battery

A type of secondary cell battery that contains a solid electrolyte. Solid-state batteries are an emerging battery technology.

solution

A mixture of two or more substances. Solutions are used in the electrolyte of different types of batteries.

source

A component that provides electrical power to a circuit. The source is the origin of electricity, such as a battery.

switch

A control device that opens and closes contacts in a circuit. Switches control when a circuit is energized and de-energized.

terminal

A conductive device within a circuit to which other components can be attached. A terminal, also known as a lead, may have either a negative or positive charge.

thermoplastic

A type of plastic that can be repeatedly heated, shaped, and cooled. Thermoplastic is often used to cover electrical wires.

time-delay fuse

A fuse that allows a specific amount of heat to build up before it opens the circuit. Time-delay fuses are used when short bursts of overcurrent are acceptable.

valence electrons

An electron in the valence, or outermost, shell of an atom. Valence electrons are easy to transfer and influence electrical conductivity.

valence shells

The outermost orbit of electrons in an atom. Valence shells with fewer electrons are more conductive.

voltages

A measure of electrical pressure or potential known as electromotive force. Voltage is measured in volts (V).

wet-cell battery

A battery that uses a liquid electrolyte. Wet-cell batteries include many secondary cell batteries.

windings

A wire that is wrapped around a core or into a coil and used to conduct current. Windings are used in a generator to form electromagnets.

work

The result of electricity flowing through resistance. Work appears in the form of heat, light, or motion.