Module Three

Battery

A DC voltage source consisting of two or more cells that convert chemical energy into electrical energy

Series circuit

A circuit with only one path for current flow.

Circuit

A complete path for current flow

Insulator

A material through which it is difficult to conduct an electric current.

Mega

A prefix used to indicate one million; for example, one megawatt is equal to one million watts

Kilo

A prefix used to indicate one thousand (for example, one kilowatt is equal to one thousand watts).

Charge

A quantity if electricity that is either positive or negative

Ohms' law

A statement if the relationships among current, voltage, and resistance in an electrical circuit (I) equals voltage (E) divided by (R). Generally expressed by I=E/R

Coulomb

A unit of electrical charge equal to 6.25 x 1018 electrons (or 6.25 quintillion electrons). A coulomb is the common unit of quantity used for specifying the size of a given charge.

Joule (J)

A unit of measurement for doing work, represented by the letter J, One joule is equal to one newton-meter (Nm)

Resistance

An electrical property that opposes the flow of current through a circuit. Resistance (R) is measured in ohms.

Voltmeter

An instrument for measuring voltage. The resistance of the voltmeter is fixed. When the voltmeter is connected to a circuit, the current passing through the meter will be directly proportional to the voltage at the connection points.

Ohmmeter

An instrument used for measuring resistance

Resistors

Any devices in a circuit that resist the flow of electrons

Matter

Any substance that has mass and occupies space

Schematic

Any type of drawing in which symbols are used to represent the components in a system

Transformers

Devices consisting of one or more coils of wire wrapped around a common core. Transformers are commonly used to step voltage up or down.

Neutrons

Electrically neutral particles (neither positive nor negative) that have the same mass as a proton and are found in the nucleus of an atom.

Solenoids

Electromagnetic coils used to control a mechanical device such as a valve.

Relays

Electromechanical devises consisting of a coil and one or more sets of contacts. Used as a switching device.

Conductors

Materials through which it is relatively easy to maintain an electric current

Electrons

Negatively charged particles that orbit the nucleus of an atom.

Watts (W)

The basic unit of measurement for electrical power, represented by the letter W.

Ohms

The basic unit of measurement for resistance, represented by the symbol similar to an upside down U

Nucleus

The center of an atom. It contains the protons and neutrons of the atom.

Voltage drop

The change is voltage across a component that is caused by the current flowing through it and the amount of resistance opposing it.

Voltage

The driving force that makes current flow in a circuit. Voltage, often represented by the letter E, is also referred to as electromotive force (emf), difference of potential, or electrical pressure.

Current

The movement, or flow, of electrons in a circuit. Current (I) is measured in amperes.

Valence Shel

The outermost ring of electrons that orbit about the nucleus of an atom.

Power

The rate of doing work, or the rate at which energy is used or dissipated. Electrical power is measured in watts.

Atoms

The smallest particles to which an element may be divided and still remain the properties of the element

Proton

The smallest positively charged particle of an atom. Protons are contained in the nucleus of an atom.

Volts (V)

The unit of measurement for voltage, represented by the letter V. One volt is equivalent to the force required to produce a current of one ampere through a resistance of one ohm

Ammeter

an instrument for measuring electrical current

Amperes (A)

the basic unit of measurement for electrical current, represented by the letter A