FOOTNOTES
[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
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