Grade 9 Science - Electricity

static charge (static electricity)

an electric charge that tends to stay on the surface of an object, rather than flowing away quickly

electrostatic series

a list of materials that have been arranged according to their ablity to hold on to electrons

electricity

a form of energy that results from the interaction of charged particles,such as electrons or ions

insulator

a material in which electrons cannot move easily from one atom to another

conductor

a material in which electrons can move easily between atoms

semiconductor

a material in which electrons can move fairly well between atoms

ground

an object that can supply a very large number of electrons from, a charged object, thus neutralizing the object

electroscope

a device for detection the presence of an electric charge

charge by friction

a process in which objects made from different materials rub against each other, producing a new static charge on each

charging by contact

generating a charge on a neutral object by touching it with a charged object

charging by induction

the creation of charge in an object by moving electrons with the electric field of a nearby charged object, and grounding the other side of the object; done without direct contact between the objects

laws of electric charges

laws that describe how two objects interact electrically when one or both are charged (same charges repel, different charges attract)

electric field

a property of the space around a charged object, where the effect of its charge can be felt by other objects

ion

a charged atom or group of atoms

lightning rod

a metal sphere or point, attached to the highest part of a building and connected to the ground

electrostatic precipitator

a type of industrial cleaner that removes unwanted particles and liquid droplets from a flow of gas

Van de Graaff generator

a device that accumulates very large charges

electric circuit

a closed path along which electrons that are powered by an energy source can flow

voltaic cell

a source of energy that generates an electric current by chemical reactions involving two different metals or metal compounds separated by a solution that is a conductor

coulomb

the quantity of charge that is equal to 6 billion billion electrons

battery

a connection of two or more cells

electrode

one of two metal terminals in a cell or battery

electrolyte

a solution or paste that conducts charge

dry cell

a cell that contains an electrolyte that is a paste

wet cell

a cell that contains a liquid electrolyte

fuel cell

a cell that generates electricity thorough the chemical reactions a fuel that is stored outside the cell

solar cell

a cell that converts sun light into electrical energy

terminal

location on a cell that must be connected to other components to form a circuit

switch

a control device that can complete or break (open or close) the circuit to which it is connected

open circuit

a circuit that contains a gap or break

electric current

the rate of movement of electric charge

ampere

the unit of electric current, equivalent to one coulomb per second

electrical resistance

the property of a substance that hinders electric current and converts electrical energy to other forms of energy

resistor

a device used in an electric circuit to decrease the current through a component by a specific amount

load

a resistor or any other device that transforms any electrical energy into heat, motion, sound, or light

potential difference (voltage)

the difference between the electric potential energy per unit of charge at two points in a circuit

volt

the unit for potential difference, equivalent to one joule (J) per coulomb (C)

circuit diagram

a diagram that uses standard symbols to represent the components and an electric circuit and their connections

series circuit

a circuit in which there is only one path along which electrons can flow

parallel circuit

a circuit in which there is more than one path along which electrons can flow

Ohm's law

A formula that says the ratio of potential difference to current is a constant called resistance

ohm

the unit for resistance, equivalent to one volt per ampere (V/A)

super conductor

a material in which electric charge can flow with no resistance

non-ohmic conductor

a material not following Ohm's law. For e.g., the filament on a bulb.

direct current (DC)

current in which charged particles travel through a circuit in only one direction

alternating current (AC)

current in which electrons move back and forth in a circuit