The joule is the energy spent in I second by a flow of 1 ampere in 1 ohm.
The horse-power is used in rating steam machinery. It is equal to 746 watts.
The kilowatt is 1,000 watts.
The units of capacitance actually used in wireless work are the microfarad, which is the millionth part of a farad, because the farad is too large a unit; and the C. G. S. electrostatic unit of capacitance, which is often called the centimeter of capacitance, which is about equal to 1.11 microfarads.
The units of inductance commonly used in radio work are the millihenry, which is the thousandth part of a henry; and the centimeter of inductance, which is one one-thousandth part of a microhenry.
Note.--For further information about electric and magnetic units get the Bureau of Standards Circular No. 60, called Electric Units and Standards, the price of which is 15 cents; also get Scientific Paper No. 292, called International System of Electric and Magnetic Units, price 10 cents. These and other informative papers can be had from the Superintendent of Documents, Government Printing Office, Washington, D. C.
WIRELESS BOOKS
The Admiralty Manual of Wireless Telegraphy. 1920. Published by His Majesty's Stationery Office, London.
Ralph E. Batcher.--Prepared Radio Measurements. 1921. Wireless Press, Inc., New York City.
Elmer E. Bucher.--Practical Wireless Telegraphy. 1918. Wireless Press, Inc., New York City.