IGCSE Physics Glossary (N-R)

NAND-gate a logic gate that gives a high output as long as both its inputs are not high
neutron a subatomic particle with no electric charge and a relative mass of 1
newton (N) the unit of force
NOR-gate a logic gate that gives a high output when neither of its inputs are high
normal the imaginary line at right angles to a surface
north seeking pole the end of a magnet that points north when the magnet is freely suspended
NOT-gate a logic gate that has only one input and the output is high if that input is not high
nuclear fission the splitting of a nucleus into two more or less equal halves
nuclear fusion the process in which two small nuclei join together to form a larger nucleus
nucleon number the number of protons plus the number of neutrons in the nucleus of an atom
nucleus (of an atom) the tiny core of an atom that contains most of the mass of the atom, made up of protons and neutrons
nuclide an atom of specified proton number and nucleon number
ohm (Ω) the unit of electrical resistance
optical centre the point in a lens where light passes through the lens without being deviated
OR-gate a logic gate that gives a high output when either of its inputs is high
pascal (Pa) the unit of pressure
pitch the position of a note on the musical scale
plane mirror a mirror with a flat surface
plum pudding model the picture of an atom as a sphere of positive charge with electrons embedded in it
potential difference (p.d.) the difference in electric potential energy per unit charge between two points
potential divider a device used to give a variable potential difference
power the rate at which work is done or energy is transformed
pressure force per unit area
primary coil the coil in a transformer across which a potential is applied
principal focus (of a lens) the point through which rays of light initially parallel to the axis of the lens pass after refraction
prism a block of material through which light can pass
proton a subatomic particle with a positive charge and a relative mass of 1
proton number the number of protons in the nucleus of an atom
radiation transfer of energy by waves or fast moving particles
radio waves part of the electromagnetic spectrum of waves that have the longest wavelength
radioactivity the spontaneous decay of unstable nuclides
range (of an instrument) the difference between the lowest value and the highest value an instrument can measure
rarefaction a region of pressure below atmospheric pressure in a sound wave
real image an image formed by a lens or mirror that the rays actually pass through
reflected ray a ray of light leaving the surface of a mirror or interface between two materials
reflection the process in which light or other radiation bounces off a mirror or other surface
refracted ray a ray of light that has passed through the interface between two materials
refraction change of direction of a wave when it goes through an interface into a different material where its speed is different
relay an electromagnetic switch
resistance the opposition of a material to the passage of current

resistance = potential difference/current

resultant force the unbalanced force when two or more forces act on an object
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