[1]Sometimes referred to as _hertz_ (abbreviated Hz), for the 19th
Century German physicist Heinrich Hertz; 1000 Hz = 1000 cps.
[2]Devised in France and officially adopted there in 1799, the metric
system uses the meter as the basic unit of length and has been
proposed for all measurements in this country.
[3]Named for the Swedish physicist Anders J. Angstrom.
[4]The wavelength, indicated by the Greek letter λ (lambda) is related
to frequency (f) in the proportion λ (in meters) = 300,000,000/f.
(The number 300,000,000 is the velocity of light in meters per
second.)
[5]Microwaves are radio waves with frequencies above 1000 megacycles per
second.
[6]Ten to 30,000,000 kilocycles per second; this is low in the
electromagnetic spectrum, but not low in terms of the radio
spectrum, which has a low-frequency classification of its own.
[7]Primitive as early radios were by today’s standards, they brought a
new era to communication at the time. Unmodulated CW (continuous
wave) transmissions and crystal receivers were used to summon
rescuers in the _Titanic_ disaster of 1912, for example.
[8]Energy = h (Planck’s constant) × frequency. Planck’s constant is the
energy of 1 quantum of radiation, and equals 6.62556 × 10⁻²⁷
erg-sec.
[9]Each photon carries 1 _quantum_ of radiation energy, which is a unit
equal to the product of the radiation frequency and Planck’s
constant (see footnote page 15).
[10]Einstein was awarded the Nobel Prize in 1921 for his 1905
explanation of the photoelectric effect (in terms of quanta of
energy) and _not_ for his relativity theory.
[11]Einstein’s theoretical explanation applies in the case of
stimulation of a single atom. In practical stimulation,
directionality is enhanced by stimulating many atoms in phase.
[12]An atomic clock is a device that uses the extremely fast vibrations
of molecules or atomic nuclei to measure time. These vibrations
remain constant with time, consequently short intervals can be
measured with much higher precision than by mechanical or electrical
clocks.
[13]The 1966 Nobel Prize in Physics was awarded to Prof. Alfred Kastler
of the University of Paris for his research on optical pumping and
studies on the energy levels of atoms.
[14]See _Accelerators_, a companion booklet in this series, for a full
account of the Stanford “Atom Smasher”.
[15]For descriptions of fission and fusion processes, see _Controlled
Nuclear Fusion_, _Nuclear Reactors_, and _Nuclear Power Plants_,
other booklets in this series.
[16]A bit is a digit, or unit of information, in the binary
(base-of-two) system used in electronic data transmission systems.
[17]See _SNAP_, _Nuclear Space Reactors_ and _Power from Radioisotopes_,
other booklets in this series, for descriptions of nuclear sources
of power for space.
This booklet is one of the “Understanding the Atom” Series. Comments are
invited on this booklet and others in the series; please send them to
the Division of Technical Information, U. S. Atomic Energy Commission,
Washington, D. C. 20545.
Published as part of the AEC’s educational assistance program, the
series includes these titles:
_Accelerators_
_Animals in Atomic Research_
_Atomic Fuel_
_Atomic Power Safety_
_Atoms at the Science Fair_
_Atoms in Agriculture_
_Atoms, Nature, and Man_
_Books on Atomic Energy for Adults and Children_
_Careers in Atomic Energy_
_Computers_
_Controlled Nuclear Fusion_
_Cryogenics, The Uncommon Cold_
_Direct Conversion of Energy_
_Fallout From Nuclear Tests_
_Food Preservation by Irradiation_
_Genetic Effects of Radiation_
_Index to the UAS Series_
_Lasers_
_Microstructure of Matter_
_Neutron Activation Analysis_
_Nondestructive Testing_
_Nuclear Clocks_
_Nuclear Energy for Desalting_
_Nuclear Power and Merchant Shipping_
_Nuclear Power Plants_
_Nuclear Propulsion for Space_
_Nuclear Reactors_
_Nuclear Terms, A Brief Glossary_
_Our Atomic World_
_Plowshare_
_Plutonium_
_Power from Radioisotopes_
_Power Reactors in Small Packages_
_Radioactive Wastes_
_Radioisotopes and Life Processes_
_Radioisotopes in Industry_
_Radioisotopes in Medicine_
_Rare Earths_
_Research Reactors_
_SNAP, Nuclear Space Reactors_
_Sources of Nuclear Fuel_
_Space Radiation_
_Spectroscopy_
_Synthetic Transuranium Elements_
_The Atom and the Ocean_
_The Chemistry of the Noble Gases_
_The Elusive Neutrino_
_The First Reactor_
_The Natural Radiation Environment_
_Whole Body Counters_
_Your Body and Radiation_
A single copy of any one booklet, or of no more than three different
booklets, may be obtained free by writing to: