DC Circuit Components 140

This class explains the function and purpose of the various components used in DC circuits.

Class Details

Class Name:
DC Circuit Components 140
This class explains the function and purpose of the various components used in DC circuits.
Number of Lessons:
Additional Language:
Related 2.0 Class:
DC Circuit Components 221

Class Outline

  • Objectives
  • Circuit Components
  • Batteries
  • Battery Chemistry
  • Types of Batteries
  • Generators
  • Piezoelectricity
  • Conductors
  • Insulators
  • Semiconductors
  • Resistors
  • Switches
  • Fuses
  • Breakers
  • Summary


  • Describe the overall purpose of circuit components.
  • Describe how batteries work.
  • Identify the components of a battery cell.
  • Distinguish between primary and secondary cell batteries.
  • Describe how generators work.
  • Describe how piezoelectric crystals work.
  • Identify common materials used as electrical conductors.
  • Describe how insulators work.
  • Describe the purpose of semiconductors.
  • Describe the purpose of a resistor.
  • Describe how common switches work.
  • Describe how a fuse works.
  • Describe how breakers work.


  • MSSC Maintenance Awareness


Vocabulary Term Definition
acid A corrosive substance with a sour flavor.
alkaline A substance that is notable for its low number of hydrogen ions.
aluminum A lightweight, highly conductive, silvery metal that is often used in long-distance power distribution.
armature The rotating portion of a generator.
arsenic A metallic element used as a doping agent or impurity in a semiconductor.
battery A device that converts chemical energy into electrical energy. Batteries are a source of direct current.
bimetallic strip Two metals with different expansion temperatures that are fused together. When heated or cooled, one will pull on the other and curl the strip.
breaker A safety device that detects excess current in a circuit. Breakers often contain a bimetallic strip that bends and trips a switch that opens a circuit.
building code Local standards dictating rules for building safety.
button-cell battery A small, button-like battery that provides power for watches and very small devices.
cell A single unit of a battery.
chemical reaction A process in which one or more substances are changed into another substance or substances.
contact A conductive part in an electrical circuit attached to a switch that opens or closes a circuit by coming in contact with or separating from the main conductor.
control A part or component in a circuit that controls the flow of electricity.
copper A reddish-brown metal that is often used as an electrical conductor in houses, buildings, and machinery.
diode An electronic device having two terminals that allows electric current to flow in just one direction.
direct current Current that flows in one direction. Direct current does not reverse the direction of flow.
direct-current generator A device that converts mechanical energy into electrical energy by magnetic induction.
doped semiconductor A semiconductor that has an added impurity to increase its conductivity.
dry-cell battery A device containing a paste that converts chemical energy into electrical energy.
electrodes The terminals, or metal ends, in a battery that have a positive or negative potential.
electrolyte A conductive solution containing an acid, an alkaline, or a salt.
electromotive series A list of metals in order of most reactive, or most likely to give up electrons, to least reactive. These metals are used in batteries.
electronics The science, technology, and engineering concerned with the flow of electrons and electric phenomena.
fixed resistor A device that resists only a specific amount of current flow.
fuse A safety device that detects excess current in a circuit. Fuses often have a component that melts and opens the circuit.
gage A standard of measurement used for determining the diameter of wire.
ground The earth or other large conducting body that serves as a source of zero electrical potential.
insulator Any material that exhibits high resistance to electrical current, such as rubber, plastic, or wood.
lead A metal connector, such as the ends of a resistor.
load The part or component in a circuit that converts electricity into light, heat, or mechanical motion. Examples of loads are a light bulb, appliance, or machine.
magnetic induction The use of magnets to cause voltage in a conductor. Magnetic induction occurs whenever a conductor passes through magnetic lines of flux.
mechanical energy Power that is produced by some force of motion, such as water power, wind power, gas power, or human power.
overcurrent An excess of current flowing through a circuit.
oxidize To remove electrons from an atom, an ion, or a molecule.
path A conductor that directs electricity in a circuit. The path is often copper wire.
piezoelectricity An electric charge produced by mechanical manipulation of a crystal. This includes striking or twisting.
PN diode A diode that has one positively charged side and one negatively charged side.
polarities Opposing charges that exist at opposite ends of an object, such as a bar magnet.
pole piece One of the magnets in a device such as a generator that helps create the magnetic field needed for magnetic induction and electricity production.
primary cell Another term for a dry-cell battery.
pure semiconductor A semiconductor that contains no added impurities.
quartz A hard, crystalline mineral made of silica.
resistor A device used in circuits to limit current flow.
Rochelle salt A crystal often used as the needle on a phonograph.
salt A chemical compound with a crystalline structure.
secondary cell Another term for a wet-cell battery.
semiconductor A material with a conductive ability that lies between that of a conductor and an insulator. At high temperatures, semiconductors act like a conductor.
sheathing A type of covering that completely wraps or encases an object.
source The device that provides electrical power to a circuit. The source is the origin of electricity, such as a power plant.
switch A device that opens and closes a circuit.
thermoplastic A plastic that may be repeatedly heated, shaped, and cooled without damage.
valence electron An electron that orbits within the outermost shell of an atom.
wet-cell battery A device containing a solution that converts chemical energy into electrical energy.