Hadron - The attraction of mass to all
other mass. Gravity is the weakest known force in nature at
Heavy ion - The nucleus of a large atom, such
as gold, with more or fewer electrons than usual, or no
electrons at all.
Hertz - Abbreviated Hz. A unit of
frequency equal to one cycle per second. One kHz = 1000 Hz. One
MHz = 106 (one million) Hz. One GHz = 109 Hz.
Hydromagnetic Wave - A wave in which both the plasma
and magnetic field oscillate.
Half-life - Length of time for half of a
sample of radioactive material to decay.
Harmonics - Frequencies produced by musical
instrument that are multiples of fundamental tone.
Heat - Quantity of energy transferred
from one object to another because of a difference in
Heat Engine - Device that converts thermal
energy to mechanical energy.
Heat of Fusion - Quantity of energy needed to
change a unit mass of a substance from solid to liquid state at
the melting point.
Heat of Vaporization - Quantity of energy needed to
change a unit mass of a substance from liquid to gaseous state
at the boiling point.
Heavy Water - Deuterium oxide used mainly in
CANDU nuclear reactors.
Heisenberg Uncertainty Principle - The more accurately one
determines the position of a particle, the less accurately the
momentum can be known, and vice versa.
Hole - Absence of an electron in a
Hooke’s Law - Deformation of an object is
proportional to force causing it.
Huygens’ Wavelets - Model of spreading of waves in
which each point on wavefront is source of circular or spherical
Hydraulic System - Machines using fluids to transmit
Hyperbola - Mathematical curve that describes
an inverse relationship between two variables.
Hypotenuse - Side opposite the right angle in a triangle.