key words Flashcards
acceleration
change of velocity per unit time
acceleration of free fall
acceleration of an object acted on only by the force of gravity
accurate
a measurement that is obtained, using calibrated instruments correctly
accuracy
how close a measurement or answer is to the true value
alpha radiation
particles that each consist of two protons and two neutrons
amplitude
maximum displacement of a vibrating particle.
annihilation
when a particle and its antiparticle meet, they destroy each other and become radiation
antibaryon
a hardon consisting of three antiquarks
antimatter
antiparticles that each has the same rest mass and, if charged, have an equal and opposite charge to the corresponding particle
antimuon
the antiparticle of the muon
antineutrino
the antiparticle of the neutrino
antinode
fixed point in a stationary wave pattern where the amplitude is a maximum
antiparticle
there is an antiparticle for every type of particle
antiquark
antiparticle of a quark
atomic number
the number of protons in the nucleus of an atom
baryon
a hardon consisting of three quarks
base units
the units that define the SI system
beta radiation
B- particles are fast-moving electrons emitted by unstable neutron-rich nuclei or by free neutrons when they decay
braking distance
the distance travelled by a vehicle in the time taken to stop it
breaking stress
ultimate tensile stress
brittle
snaps without stretching or bending when subject to stress
centre of mass
the centre of mass of a body has no turning effect
charge carriers
charged particles that move through a substance when a pd is applied across it
circuit rule current
- current passing through two or more components in series
2. at a junction its split
curcuit rules pd
- two or more components in series, the total pd across all the components is equal to the sum of pd across each components
2 the sum of the emfs around a complete loop in a curcuuit= the sum of the pds round the loop
coherent
two sources of waves are coherent if they emit waves with a constant phase difference
conservation rules
conversion of energy, momentum, charge, baryon number and lepton number
couple
pair of equal and opposite forces acting on a body but not along the same line
critical angle
the angle of incidence of a light ray must exceed the critical angle for total internal reflection to occur
critical temperature of a superconducting material
temperature at and below which its resistivity is zero
cycle
interval for a vibrating particle from a certain displacement and velocity to the next time the particle that has the same displacement and velocity
de Broglie hypothesis
matter particle have a wave-like nature characterised by the de Broglie wavelength
de Broglie wavelength
the wavelength of a matter particle= h/p
de-excitation
process in which an atom loses energy by photon emission, as a result of an electron inside an atom moving from an outer shell to an inner shell
density of a substance
mass per unit volume of the substance
diffraction
spreading of waves on passing through a gap or near an edge
diffraction grating
a plate with many closely rules parallel slits on it
dispersion
splitting of a beam of white light by a glass prism into colour
displacement
distance in a given direction
drag force
the force of fluid resistance on an object moving through the fluid
ductile
stretches easily without breaking
efficiency
the ratio of useful energy transferred by a machine or device to the energy supplied to it
effort
the force applied to a machine to make it move
elastic limit
point beyond which a wire is permanently streched
elasticity
property of a solid that enables it to regain its shape after it has been deformed or distorted
electrolysis
process of electrical conduction in a solution or molten compound due to ions moving to the oppositely charged electrode
electrolyte
a solution or molten compound that conducts electricity
electromagnetic interaction
interaction between two charged objects
electromagnetic wave
a wavepacket or photon consisting of transverse electric and magnetic waves in phase at right angles
EMF (electromotive force)
the amount of electrical energy per unit charge produced inside a source of electrical energy
electron capture
process in which an inner-shell electron of an atom is captured by the nucleus
electron volt
amount of energy equal to 1J defined as the work done when an electron is moved through a pd of 1V
endoscope
optical fibre device used to see inside cavities
energy
the capacity to do work
energy levels
the energy of an electron in an electron shell of an atom
equilibrium
state of an object when at rest or in uniform motion
error bar
representation of an uncertainty on a graph
error of measurement
uncertainty of a measurement
exitication
process in which an atom absorbs energy without becoming ionised as a result of an electron inside an atom moving from an inner shell to the outer shell
first harmonic
pattern of stationary waves on a string when it vibrates at its lowest possible frequnecy
fluorscene
glow of light from a substance exposed to ultaviolet radiation
force
any interaction that can change the velocity of an object
free body force diagram
a diagram of an object showing only the forces actong on the object
frequency
the number of cycle of a wave that pass a point per second
friction
force opposing the motion of a surface that moves or tries to move across another surface
gamma radation
high-energy photons emitted by unstable nuclei or produced in particle annihilations
gravitional field strength
force of gravity per unit mass on a small object
ground state
lowest energy state of an atom
hardon
particles and antiparticles that can interact through the strong interaction
hooke’s law
the extension of a spring is proportional to the force needed to extend it
inertia
resistance of an object to change of its motion
interfernce
formation of points of cancellation and reinforcement where two coherent waves pass through each other
internal resistance
resistance inside a source of electrical energy
ion
a charged atom
ionsation
process of creating ions
isotopes
atoms of an element with different number of neutrons and same number of protons
