*GCSE Physics (AQA)

P1

energy

The ability to do work

energy store

a form of energy

kinetic energy

energy which a body possesses by virtue of being in motion

gravitational potential energy

energy an object possesses because of its position in a gravitational field

thermal energy

the internal energy present in a system due to its temperature

elastic potential energy

the energy stored in elastic materials as the result of their stretching or compressing

emit

to give off or send out

absorb

to take in

conservation of energy

The principle that energy cannot be created or destroyed

closed system

A system in which energy, but not matter, is exchanged with its surroundings.

pendulum

A hanging mass that swings back and forth when pulled to one side and let go.

work

(joules, J) Force x Distance, the exertion of force overcoming resistance or producing molecular change

joules

the SI unit of work or energy, equal to the work done by a force of one newton when its point of application moves one metre in the direction of action of the force

force

(newtons, N) A push or a pull

Newtons

the SI unit of force. It is equal to the force that would give a mass of one kilogram an acceleration of one metre per second per second

kilograms

the SI unit of mass, equivalent to the international standard kept at Sèvres near Paris

mass

(kilograms, kg) the quantity of matter which a body contains

weight

(newtons, N) the force exerted on the mass of a body by a gravitational field.

metres

(m) a measure of distance or displacement.

time

(seconds, s) the indefinite continued progress of existence and events that occur in apparently irreversible succession from the past through the present to the future.

unit

standards for measurement of physical quantities that need clear definitions to be useful

precision

refers to the closeness of two or more measurements to each other

accuracy

the degree of closeness of measurements of a quantity to that quantity's true value.

friction

the resistance that one surface or object encounters when moving over another.

gravitational field strength

(g) The force per unit mass experienced by a mass placed in a gravitational field.

speed

(meters/second, m/s) The distance an object travels per unit of time, Distance / Time

spring constant

(k) a parameter that is a measure of a spring's resistance to being compressed or stretched

useful energy

Energy converted by a device into the form(s) the device was designed for.

wasted energy

Energy converted by a device into the form(s) the device was NOT designed for.

dissipate

to spread out and become less concentrated

efficiency

The percentage of the input work that is converted to output work. = useful output energy supplied by device (J) / total input energy of the device (J) x 100

order of magnitude

estimate of quantity to the nearest power of ten

power

(work/time, J/t) the rate of doing work

Watts

(W) the SI unit of power, equivalent to one joule per second

P2

thermal conductivity

The ability of an object to transfer heat

conduction

Form of heat transfer where heat energy is directly transferred through direct contact.

conductor

A material that allows heat and electricity to pass through it.

insulator

A material that does not allow heat or electrons to move through it easily.

infrared radiation

Electromagnetic waves with wavelengths that are longer than visible light but shorter than microwaves; heat radiation

temperature

(Celsius, C) A measure of the average kinetic energy of the particles in a sample of matter

Celsius

(C) a scale of temperature on which water freezes at 0° and boils at 100° under standard conditions.

Kelvin

(K) the SI base unit of thermodynamic temperature, equal in magnitude to the degree Celsius, where 0 is defined as absolute zero; [K] = [°C] + 273.15

absolute zero

The coldest temperature, 0 Kelvin or -273.15 Celsius, that can be reached. It is the hypothetical temperature at which all molecular motion stops.

reflect

the change in direction of a wavefront at an interface between two different media so that the wavefront returns into the medium from which it originated; bouncing back

transmit

to send on, pass along, send out

black body

An ideal absorber of electromagnetic radiation that would absorb all the radiation that was incident upon it. Would also be an ideal emitter, and would emit electromagnetic radiation with a spectrum that depended only on the temperature of the body.

black body radiation

radiation from a theoretical perfect emitter (and absorber) of radiation at all wavelengths.

specific heat capacity

(joules, J) the amount of heat energy required to raise the temperature of one gram of substance by one degree celcius

convection

Process by which, in a fluid being heated, the warmer part of the mass will rise and the cooler portions will sink; the transfer of heat by the movement of a fluid

vacuum

An empty space where no particles of matter exist

P3

biofuel

fuel created from living matter, such as trees

renewable

A natural resource that can be replaced at the same rate at which the resource is consumed

carbon-neutral

A process, or series of processes, in which as much carbon dioxide is absorbed from the air as is given out.

nuclear fuel

an energy source that results from splitting atoms

nucleus

The central core of an atom which contains protons and neutrons.

electron

A subatomic particle that has a negative charge

reactor core

Term encompassing fuel rods, control rods and absorber rods of a nuclear reactor which together with the moderator substance are in a steel vessel through which coolant is pumped.

wind power

The use of a windmill to drive an electric generator

wave power

electrical power produced from ocean waves that are used to turn an electrical generator

hydroelectric power

Electricity generated by flowing water

tidal power

Electricity generated by the movement of sea water caused by the tides

solar power

energy from the sun that is converted into thermal or electrical energy

geothermal energy

Energy from steam or hot water produced from hot or molten underground rocks.

P4

proton

A subatomic particle that has a positive charge and that is found in the nucleus of an atom

neutron

A subatomic particle that has no charge and that is found in the nucleus of an atom

ion

A particle that is electrically charged (positive or negative)

electric field

a field of force surrounding a charged particle

static electricity

An accumulation of electric charge on an insulated body.

induction

The transfer of charge without contact between materials

charge

(coulomb, Q) A measure of the extra positive or negative particles that an object has.

current

(amperes, A) the rate of flow of electric charge; current = voltage/resistance; I = V/R; amperes = volts/ohms

electrochemical cell

a device capable of generating electrical energy from chemical reactions

battery

consisting of two or more electrochemical cells

switch

A device for making, breaking, or changing the connections in an electrical circuit.

indicator

designed to emit light as a signal when current passes through it; ex. a bulb.

diode

A device that permits current to flow through it in only one direction.

LED

light-emitting diode; permits current to flow through it in only one direction, emits light when current flows through it

ammeter

A meter that measures the flow of electrical current in amperes

fixed resistor

Resistors that have a value that cannot be changed.

variable resistor

A resistor whose value can be varied between its minimum and maximum values.

fuse

Electrical device that can interrupt the flow of electrical current when it is overloaded, often by melting

heater

Converts electrical energy to heat

voltmeter

A device used to measure voltage, or electrical potential energy difference

charge flow

Negative to positive terminal; (Q) = current (A) x time (s)

coulombs

(Q) the SI unit of electric charge, equal to the quantity of electricity conveyed in one second by a current of one ampere.

amperes

(A) a unit of electric current equal to a flow of one coulomb per second.

volts

(V) the SI unit of electromotive force, the difference of potential that would carry one ampere of current against one ohm resistance.

potential difference

voltage; the work done when a coulomb of charge passes between the points; voltage (volts, V) = work done (joules, J) / charge (coulombs, Q)

component

any basic discrete device or physical entity in an electronic system

series circuit

A circuit in which all parts are connected end to end to provide a single path of current.

parallel circuit

A closed electrical circuit in which the current is divided into two or more paths and then returns via a common path to complete the circuit.

resistance

(ohms, Ω) a material's opposition to the flow of electric current.

ohms

(Ω) the SI unit of electrical resistance, transmitting a current of one ampere when subjected to a potential difference of one volt.

thermistor

A resistor that changes its resistance with a change of temperature

light-dependant resistor

A resistor that changes its resistance with a change of light intensity

P5