Science 9- Unit D - Electrical Principles and Technologies

Brushes

Mechanisms that make electrical contact with the moving commutator in motor.

Multimeters

Meter that can measure voltage, current, or resistance in a circuit

Ammeters

Meter used to measure electrical current in amperes (amps)

Microcircuits/Integrated Circuits

Miniature electronic circuits, esp. ones in which a number of permanently connected components are contained in one small chip of semiconducting material.

Binary Numbers

Number having two as its base so only having ones and zeros.

Biomass

Organic Matter, such as food or agricultural waste, used as an energy source.

Electrochemical Cell

Package of chemicals designed to produce small amounts of electricity; produces electricity from chemical reactions.

Proton

Positively charged particle in the nucleus of an atom

Secondary Cells

Rechargeable cell

Armature

Rotating shafts and coils in a motor or generator.

Circuit Breakers

Special wire that heats up and turns off switch when excess current flows through an electrical circuit.

Commutator

Split ring in a motor that breaks the flow of electricity for a moment and then reverses the connection of the coil.

Nuclear Fission

Splitting of atoms, which transforms them into lighter elements and releases large amounts of energy.

Electrical Current

Steady flow of charged particles.

Electrical Discharge

Sudden transfer of electrical charge from one object to another, indicated by a spark.

Dry Cells

The electricity producing cells that we use every day in flashlights and portable radios

Amperes (A)

The unit of electrical current

Fuses

Thin piece of metal that melts to break an electrical circuit when excess current flow occurs.

Voltage Drop

Voltage across a resistor or other device in a circuit.

Superconductors

a perfect conductor; substance with no resistance to flow

Renewable Resources

a resource such as coal or resource such as water or wind energy that is continually replenished and therefore can be used indefinitely

Short Circuit

accidental low-resistance connection between two points in a circuit, often causing excess current to flow.

Potential Difference

change in the potential energy of electric charge compared to its potential energy at a reference point.

Kilowatt Hour

commonly used unit of electrical energy, equal to a power consumption of 1000 W for one hour.

Rheostat

continuously variable resistor used to regulate electric current

Alternating Current

current that flows back and forth 60 time per second; this is the current used in homes.

Electrolysis

decomposition of a substance by an electric current

Resistor

device having resistance to the passage of electrical current, often used to control current in a circuit

Transformers

device that changes electricity at one voltage into electricity at a different voltage; a step-up transformer increases the voltage; a step down transformer decreases the voltage.

Geothermal Energy

energy derived from the internal heat of earth.

Fly Ash

fine airborne ash produced by burning coal or other solid fuels

Fossil Fuels

fuel formed form dead plants and animals; coal,oil, and natural gas.

Law of Conservation of Energy

fundamental principle that energy cannot be created or destroyed.

Electromagnetic Induction

generation of electric current in a conductor by a changing magnetic field.

Voltmeter

instrument used for measuring potential difference in volts.

Parallel Circuits

A closed circuit in which the current divides into two or more paths before recombining to complete the circuit.

Voltage

A measure of how much electrical energy a charged particle carries.

Transistors

A semiconductor device with three connections, capable of amplification in addition to rectification.

Battery

A set of cells connected together

Static Electricity

A stationary electric charge

Energy

Ability to do work.

Ion

An atom or group of atoms that has become electrically charged through the loss or gain of one or more electrons and has a negative or positive charge.

Rechargeable Cell

Cell that produces electricity by means of a chemical reaction that can be reversed by using an external source to run electricity back through the cell

Primary Cells

Cell that produces electricity by means of a chemical reaction that cannot be reversed

Series Circuit

Circuit in which there is only a single pathway for the current so the same current passes through all the components.

Electromagnet

Coil of insulated wire (usually wrapped around a soft iron core) that becomes a magnet when current flows through it.

Circuit

Complete path that charged particles flow through.

Charge Separation

Concentration of like charges in specific areas of a neutral object; for example, a negatively charged object brought close to a wall repels the electrons in the wall, leaving the area of the wall closest to the object positively charged.

Electrode

Conductor through which electric current enters or leaves a device or material

Galvanometers

Device for measuring and detecting small electric currents

Load

Device in a circuit that converts electrical energy to another form of energy (eg. a light bulb)

Schematic

Diagram using standardized symbols to show the components and connections in a circuit.

Wet Cells

Electrochemical primary cell having a liquid electrolyte

Electrical Energy

Energy of charged particles; transferred when electrons travel from place to place.

Chemical Energy

Energy stored and released when chemicals react; a form of potential or stored energy.

Millivoltmeters

Instrument used to measure small voltages.

Electron

Invisible negatively charged particle that orbits the nucleus of an atom.

Ohm's Law

Law stating that, as long as the temperature remains constant, the resistance of a conductor remains constant, and the current is directly proportional to the voltage applied; R = V/I or I = V/R or V = IR

Electrolyte

Liquid or paste that conducts electricity because it contains ions

Turbine

Machine that uses the flow of a fluid such as: steam, water or air to rotate a shaft.

Neutral

(in chemistry) pH of 7; a neutral substance is neither an acid nor a base.

Resistance

measure of how difficult it is for electrons to flow through a substance; unit of measure is ohm

Nonrenewable Resource

natural gas that cannot be replenished

Fuel Cells

primary cells that generates electricity directly from a chemical reaction with a fuel.

Power

rate at which a device converts energy.

Variable Resistor

resistor whose resistance can be changed by adjusting the portion of the resistor the current travels through

Electrochemistry

study of chemical reactions involving electricity

Insulators

substance that strongly resists the flow of electricity

Watt

the unit of power, equal to one joule per second.

Ohms

the unit of resistance

Volt

the unit of voltage

Electroplating

use of electricity to coat a thin layer of metal onto an object

Sustainability

use of resources at a rate that can be maintained indefinitely without depleting the resources or harming the environment.