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energy
The ability to do work
energy store
a form of energy
kinetic energy
energy which a body possesses by virtue of
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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
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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
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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.
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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
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alternating current
an electric current that changes direction at regular intervals
direct current
an electric current that flows in one direction steadily
live wire
The brown wire in a cable or plug; carries a high voltage around the house
neutral wire
The blue wire in a cable or plug; carries current away from the component
oscilloscope
a laboratory instrument that is capable of displaying a graph of voltage as a function of time
frequency
1/time taken for 1 cycle
earth wire
It connects the casing of the electrical appliance to ground via the earth terminal of the plug. Its insulation is coloured green and yellow. In the event of an appliance malfunction resulting in the casing becoming live, it provides a route to ground for the current. This will help prevent electric shock.
resistance heating
As current flows through a conductor, heat is produced by the resistance of the conductor.
P6
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density
Mass / Volume; a measure of how much mass is contained in a given volume.
volume
A measure of the size of a body or region in three-dimensional space
meniscus
The curved upper surface of a liquid column that is concave when the containing walls are wetted by the liquid and convex when not.
measuring cylinder
Used to measure the volume of liquids accurately.
gas
A state of matter with no definite shape or volume
solid
A form of matter that has a definite shape and volume
liquid
A state of matter that has no definite shape but has a definite volume.
physical changes
Any change that DOES NOT alter the chemical composition of a substance.
vaporisation
When an substance changes from liquid to gas
condensation
The change from a gas to a liquid
sublimation
a change directly from the solid to the gaseous state without becoming liquid
freezing
The change of state from a liquid to a solid
deposition
Change from a gas directly to a solid
conservation of mass
The principal stating that matter is not created or destroyed during a chemical reaction
melting point
The temperature at which a solid becomes a liquid
boiling point
The temperature at which a liquid changes to a gas
freezing point
The temperature at which a liquid changes into a solid
latent heat
heat absorbed or radiated during a change of phase at a constant temperature and pressure
internal energy
sum of the kinetic and potential energies of all particles in the system
specific latent heat of fusion
amount of energy per unit mass required to change phase of a substance from a solid to a liquid at constant temperature and pressure
specific latent heat of vaporisation
amount of energy per unit mass required to change phase of a substance from a liquid to a gas at constant temperature and pressure
gas pressure
results from the force exerted by a gas per unit surface area of an object
Brownian motion
the random movement of particles in a fluid
pressure
(pascals, Pa) force / area; Force per unit area
Boyle's law
P1V1 = P2V2; the relationship between the pressure and volume of a gas at constant temperature is inversely proportional; when volume increases, pressure decreases.
pascals
(Pa) the SI unit of pressure, equal to one newton per square metre
P7
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Geiger counter
Radiation detector that produces a click or a flash of light when a charged particle is detected.
alpha radiation
Radiation that is made up of alpha particles; 2 protons and 2 neutrons. High ionisation, but low penetration. Is easily blocked with paper.
beta radiation
Consists of electrons, is halted by an aluminum plate that is a few mm thick or a couple of mm of lead
gamma radiation
High-energy electromagnetic radiation emitted by the nuclei of radioactive atoms.
radioactivity
the emission of ionising radiation or particles caused by the spontaneous disintegration of atomic nuclei
plum pudding model
J.J Thomsons model of an atom, in which he thought electrons were randomly distributed within a positively charged cloud
photon
A particle packet of electromagnetic radiation with no mass that carries a discrete amount of energy
atomic number
The number of protons in the nucleus of an atom
mass number
the sum of the number of neutrons and protons in an atomic nucleus
isotopes
Atoms of the same element that have different numbers of neutrons.
alpha particle
A cluster of 2 protons and 2 neutrons emitted from a nucleus in one type of radioactivity
beta particle
a high-speed electron or positron emitted in the decay of a radioactive isotope
neutron emission
a type of radioactive decay where a neutron is released from the nucleus, decreasing the mass number by one
ionisation
the process where an atom loses or gains an electron [Show Less]