Key Terms Flashcards
Acceleration
The rate of increase of velocity with time
Air resistance (Drag)
The force opposing the motion of bodies moving through the air
Alpha particle
A type of nuclear radiation consisting of a helium nucleus ejected from an unstable nucleus
Alternating current
A current that continually changes direction
Ammeter
An instrument used to measure the size of current in a circuit
Amplified
Increased in size or power
Amp
The unit of electric current
Analogue signals
Electrical signals that have continuously variable values
Angle of incidence
The angle measured between a ray of light reflected from a surface and the normal
Balance
Equal in size but opposite in sign, therefore summing to zero (forces, charge, etc)
Becquerel
The rate of disintegration of a radioactive substance; one disintegration per second
Beta particle
A type of nuclear radiation consisting of a high speed electron emitted from an unstable nucleus
Braking distance
The distance a vehicle travels before coming to rest after the brakes have been applied
Brownian motion
The continuos, random, jerky motion of pollen grains as observed by botanist Robert Brown
Cell mutation
A change in the function of a living cell, sometimes caused by ionising radiation
Centre of gravity
The point in a body through which the whole of its weight appears to act
Chain reaction
An escalating nuclear process in which each decay of an unstable nucleus triggers two or more unstable nuclei to decay
Circuit breakers
The modern equivalent of a fuse; breaks the path of a circuit when a set current is exceeded. Can be reset by the push of a switch once the fault is repaired.
Comet
A relatively small ice and rock body orbiting the song with an elongated (eccentric) orbit
Conductors
Materials that allow electricity to pass through them easily
Contact force
The forces acting on bodies in contact
Control rods
Used in nuclear reactors to slow down the rate of nuclear fission, or stop the fission process completely, by removing neutrons from the process
Controlled nuclear fission
An uncontrolled fission involves the release of vast amounts of energy in a very short time, which would result in an explosion. A controlled nuclear fission prevents this
Critical angle
Light arriving at a boundary between any material, in which light travels more slowly than air, and air at an angle of greater than the critical angle, is TIR
current
The rate of flow of electric charge
Density
The mass per unit volume of a substance
Diffraction
The curving of waves as they pass the edges of objects
Digital signals
A digital signal that has only 2 possible values
Displacement
Distance moved in a specific direction (a vector quantity)
Distance
Distance moved without considering direction (a scalar quantity)
Double insulation
Having an outer casing which is an electrical insulator so there is no exposed metal casing
Drag force
The force that opposes the motion of an object through a gas or liquid
Earthed
Having a very low resistance connection to the general mass of the earth, taken always as being a 0V
Efficiency
A measure of how effectively energy is transformed into a useful form
Elastic
Able to return to its original size and shape after having been deformed
Elastic Limit
The point at which a stretched spring or wire no longer obeys Hooke’s law
Electric charge
The property of particles that causes electric effects
EM waves
Waves that require no material medium in which to travel and carry energy
EM spectrum
The family of EM waves, ranging from radio waves to gamma and cosmic waves
Electron
Extremely small particle carrying negative charge and making up the outer shell or shells of an atom
Endoscope
A fibre optic device used to image the inside of living bodies as a diagnostic tool
Energy
Is required to do work
Evaporation
The process by which liquids change into gases
Extension
In springs, this is the increase in length that results from applying a force to stretch the spring
Fissile
Referring to unstable materials; something that can be readily split or will split spontaneously
Force
A push or a pull which causes a change in the state of motion of a body or the shape of the object
Fossil Fuels
Fuels formed from dead organic matter over millions of years, including gas, oil and coal
Free Electrons
Electrons which are not bound to any particular atom, and are therefore free to move and enable an electric current to flow through a material
Frequency
The number of waves produced in one second
Friction
The force that opposes motion between two surfaces
Fuse
A length of wire designed to melt when a specified current value is exceeded, thus breaking the circuit
Galaxy
A group of many billions of stars rotating around a common centre
Gamma rays
Highly penetrating EM radiation produced when an unstable atom disintegrates
Geothermal energy
Heat energy produced by nuclear processes in the earth’s core
Gradient
The slope of a graph line measured by y/x
Gravitational field strength
The force in newtons exerted per kilogram of mass by gravity (on Earth this is 10 N/kg)
Half-Life
The time taken for half the atoms in a sample of radioactive material to decay
Hard magnetic materials
Materials that retain their magnetism well
Hydroelectric power
Power produced using the potential energy of water stored in reservoirs
Hydroelectricity
Electricity produced by generators using hydroelectric power
Inelastic
Materials that are unable to return to their original shape after deformation by a force
Infrared
A part of the EM spectrum; radiation emitted by hot objects
Insulators
Materials that electricity cannot pass through
Joule
The unit of energy. 1 joule is the amount of work done when a force of 1 newton is applied through a distance of 1 metre
Kelvin
The scale of temperature with 0 set as the lowest possible temperature (absolute 0), which is -273°C
Light waves
A part of the EM spectrum that can be detected by the human eye
Longitudinal waves
Waves in which the particles of the medium move backwards and forwards along the same line as the direction of transfer of energy
Loudness
The power of strength of a sound, depending on the amplitude of the sound wave
Magnetic
Possessing the ability to attract iron and its compounds
Mechanical waves
Waves that require a material medium through which energy may be transferred
Microwaves
A part of the EM spectrum; used to heat water and in telecom systems
Moderator
A material used in nuclear reactions to slow the neutrons to allow the reaction to take place; often made of graphite
Moons
Natural satellites held in orbits around planets by the force of gravity
Motor rule
The rule devised by Fleming to predict the direction of the force produced on a wire when it carries current in a magnetic field
Negative electric charge
The type of charge possessed by an electron
Neutral
Having no overall charge
Neutron
Uncharged particle found in the nucleus of the atom
Normal
Perpendicular to, as in the normal drawn as a construction line
Normal reaction
A contact force acting at right angles to a surface
Ohm
Unit of resistance; the resistance of a conductor that passes a current of 1 amp when a voltage of 1 volt is applied across it
Optical fibre
A thing glass tube designed to carry information in the form of light using TIR
Parallel circuit
A circuit with two or more conducting paths between any two points in the circuit
Parent nuclide
An unstable nucleus that decays and splits into two or more lighter nuclei
Partially elastic
Description of a collision in which kinetic energy is not conserved after the colliding bodies have separated
Period
The time taken for one complete cycle of an oscillation or wave
Pitch
How high a musical note is; related to the frequency of the sound
Planets
Massive objects held in regular orbit around a star by the force of gravity
Positive electric charge
The type of charge possessed by the proton
Power
The rate of transfer or conversion of energy
Pressure
Force acting per unit area
Proton
A positively charged particle found in the nucleus of an atom
Radio waves
A part of the EM spectrum; used in communication and radio and TV transmission
Reaction time
The time taken until there is a conscious response to humans to some event
Resistance
A measure of how difficult it is for current to pass through a part of a circuit
Resultant force
The net force acting on a body when two or more forces are unbalanced
Sankey diagram
Diagrams used to represent the relative size of energy conversions that take place in a process or system
Satellites
Man-made objects held in orbit around a planet by the force of gravity
Scalar
A quantity with magnitude but no specific direction
Second
The base unit of time measuremement
Series circuit
A circuit with only one path for an electric current to flow
Soft magnetic materials
Materials that are easy to magnetise and demagnetise
Solar power
Power obtained from the energy transferred by the EM waves from the sun
Sound waves
Longitudinal waves in gases, liquids and solids with frequencies in the range 20Hz to 20kHz
Speed
Distance travelled per unit of time
Star
Huge nuclear fission explosions releasing vast amounts of energy as light, heat and other forms of EM radiation
Tension
The force in stretched materials
Thermal radiation
Heat radiation
Thinking distance
The distance travelled by a moving vehicle in the time that it takes for the driver to react to an emergency before applying the breaks
Tidal power and wave energy
Power obtained from the rise and fall of the oceans due to tidal motion
Transformers
Electromagnetic devices used to either step-up or step-down the size of alternating voltage electricity suplies
Transverse waves
Waves in which the particles of the medium move at right angles to the direction of transfer of energy. EM waves are transverse waves
UV
Part of the EM spectrum; used in forensics and tanning
Unbalanced
Not adding up to zero (eg. unbalanced forces)
Universe
The system comprising of every galaxy
Upthrust
The upward force that acts on an object because it has displaced a volume of liquid or gas
Vector
A quantity that has both size and direction
Velocity
The rate of increase of distance travelled in a specified direction with time
Virtual image
The image formed in mirrors that appears to be behind the mirror. Any image that is not the actual source of real rays of light
Viscous drag
The force that opposes the motion of an object through a liquid
Visible light
EM waves in the range of frequencies that can be detected by the human eye
Voltage
A measure of the energy converted per unit of charge passing through a component; the measure of the amount of energy transferred to electrical form per unit by an electrical power supply
Voltmeter
A measuring instrument for measuring the voltage between two points in a circuit
Volt
The unit of voltage; 1 volt is equal to 1 joule of energy per coulomb of charge passed through a component
Watt
The unit of power; equal to the rate of transfer of energy of 1 joule per second
Weight
The force acting on a body due to its presence in a gravitational field
Wind power
Power obtained from the kinetic energy of moving air
Work
The transfer of energy to a body. Mechanical work is the transfer of energy which occurs when a force is applied through a distance in the direction of the force
X-rays
EM waves; can be used medically or industrially to see inside people or infrastructure
