science- term 4

electric charge

a characteristic of a unit of matter that expresses the extent to which it has more or fewer electrons than protons.

static electricity

electricity produced by friction

triboelectric series

a type of contact electrification on which certain materials become electrically charged after they are separated from a different material with which they were in contact

friction

the resistance encountered when one atom is moved in contact with another

lightning

an electrical discharge caused by imbalances between storm clouds and the ground

current electricity

an electric current is a stream of charged particles, such as electrons or ions, moving through an electrical conductor

conductor

conductor is an object or type of material that allows the flow of charge in one or more directions (metal)

insulator

a material in which electric current does not flow freely. the atoms of the insulator have tightly bound electrons which cannot readily move.

resistor

a resistor is an electrical component that limits or regulates the flow of electrical current in an electronic circuit. resistors can also be used to provide a specific voltage for an active device such as a transistor.

circuit

an interconnection of electrical components or a model of such an interconnection, consisting of electrical elements. an electrical circuit is a network consisting of a closed loop, giving a return path for the current.

electron

an electron is an elementary particle that has a negative charge and is a constituent of all atoms.

proton

a subatomic particle found in the nucleus of every atom. the particle has a positive electrical charge, equal and opposite to that of the electron

neutron

a subatomic particle found in the nucleus of every atom except that of simple hydrogen. the particle derives its name from the fact that it has no electrical charge; it is neutral.

voltage

the rate at which energy is drawn from a source that produces a flow of electricity in a circuit

potential difference

the external work needed to bring a charge from one location to another location in an electric field. electric potential difference is the change of potential energy experienced by a test charge that has a value of +1 .

resistance

a force that counteracts the flow of current

ammeter

instrument for measuring either direct (DC) or alternating (AC) electric current, in amperes

voltmeter

instrument used for measuring electric potential difference between two points in an electric circuit. it is connected in parallel.

series circuit

comprises a path along which the whole current flows through each component. a parallel circuit comprises branches so that the current divides and only part of it flows through any branch.

parallel circuit

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

short circuit

circuit that allows a current to travel along an unintended path with no or very low electrical impedance. this results in an excessive current flowing through the circuit

circuit breaker

an electrical safety device designed to protect an electrical circuit from damage caused by an overcurrent or short circuit.

fuse

electrical safety device that operates to provide overcurrent protection of an electrical circuit.

ohm's law

states that the voltage across a resistor is directly proportional to the current flowing through the resistance.

ac

alternating current is an electric current which periodically reverses direction and changes its magnitude continuously with time in contrast to direct current which flows only in one direction.

dc

one-directional flow of electric charge

double insulation

double or reinforced insulation is another method of protection against electric shock, consisting of an extra layer of supplementary insulation over the basic insulation

mains supply

a general-purpose alternating-current electric power supply. it is the form of electrical power that is delivered to homes and businesses through the electric grid in many parts of the world

earth wire

a conductor that provides a low-impedance path to the earth to prevent hazardous voltages from appearing on equipment (high voltage spikes)

active wire

electrical wire transports current (power) from the meter box through to household switches, powerpoints and appliances

3 pin plug

designed so that mains electricity can be supplied to electrical appliances safely

ohmic conductor

electrical conductors that follow Ohms law. In other words there is a linear relationship between voltage and current for all values.

non-ohmic conductor

the current flowing through the conductor and the voltage across the device do not have linear relationship