T

tachograph - device fitted in the cab for recording the speeds of lorries and buses
tachometer - a device for measuring angular speeds.
tangent - ratio of opposite side over adjacent side of a triangle
tectonic plate - moveable section of the Earth's crust
temperature - a measure of the heat energy in an object
tera - one million million (10¹²)
terminal - in electricity, place to attach a lead
terminal - final or maximum
terminal speed - the maximum speed that an object can reach when falling through a fluid
terminator - the line on the Moon (or other body) dividing light from darkness (day from night)
terrestrial - in, on or of the Earth, as in 'terrestrial observatory' – ground based observatory
tesla - unit of magnetic flux density
theory - convincing and proved (idea) hypothesis
thermal - connected with heat
thermal capacity - heat energy need to raise the temperature of an object by 1 ^oC
thermal conductivity (k) - property defining the heat flow through a body (dQ/dt = - kAdq/dx)
thermal neutrons - neutrons with speeds similar to those of molecules in a gas at room temp.
thermionic - as in 'thermionic emission', emission of electrons from a hot metal wire
thermistor - component with a resistance that changes markedly with temperature
thermocouple - thermometer made by the junction of two metals - e.m.f. generated there
thermodynamics - the branch of physics dealing with heat, work and internal energy
thermometer - instrument for measuring temperature
thermostat - a device that keeps something at a steady temperature
three phase - electrical supply with there equal a.c phases, 120^o 'apart'
threshold frequency - the minimum frequency of radiation needed to cause photoelectric emission
thrust - the force pushing a vehicle, as in 'the thrust of a rocket'
thunder - noise made by expansion and contraction of air during a lightning flash
time constant - time to reduce the voltage of a circuit to 1/e of the original value
time dilation - time is not absolute but relative to the motion of the observers
Titania - moon of Uranus
tolerance - accuracy to which something (e.g. a resistor) is made
ticker timer - school laboratory timing device using ticker tape
timbre - quality, as in a musical note
Titan - moon of Saturn
tokomak - type of nuclear fusion reactor using a toros and a magnetic field
toros - doughnut shaped chamber , used in some fusion reactors
torque - moment of a couple (Force x perpendicular distance between the forces)
torsion - stretching. The force that is stretching an object.
total - complete
total internal reflection - internal reflection of all the light at a boundary with a less dense material
tracer - radioactive isotope put in a liquid to follow its flow e.g. rivers or blood
transducer - a device for converting non-electrical signals into electrical signals e.g. microphone
trajectory - track or path of a projectile
transformer - device for changing one a.c voltage into another, step up or step down
transient - only lasting for a short time
transistor - three element component. Controls large current by small voltage change
transit - passage of a planet across the face of the Sun
transmit - give out or allow to pass through
transmutation - nuclear change from one element to another
translation - movement of a body without rotation
translucent - material that is transparent but gives a fuzzy view, indistinct
transparent - a material that a wave (e.g. light) can pass through. A clear view, undisturbed.
transverse - vibration across the direction of motion, as in a transverse wave
triple point - point where the solid, liquid and vapour phases of a substance are in equilibrium
troposphere - Earth's atmosphere below about 8 km
travelling wave - a wave where the amplitude at any point is changing as the wave moves past
tritium - a 'heavy' isotope of hydrogen, the nucleus contains one proton and two neutrons
trough - 'lowest' point of a wave
tsunami - water wave generated at sea by an earthquake
tungsten - hard metal with high melting point: light bulb filaments, X ray tube targets
tuning fork - two pronged metal device that gives out a particular note when struck
turbulence - irregular movement in a moving fluid
twinkling - flickering of the light from a star due to movements in the Earth's atmosphere