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People Behind the Science

Benjamin Franklin (1706–1790)

enjamin Franklin was the first great enabled Franklin to put the whole topic on
BU.S. scientist. He made an important a very sound basis. It was said that he found
contribution to physics by arriving at an electricity a curiosity and left it a science.
understanding of the nature of electric In 1752, Franklin carried out his
charge, introducing the terms positive and famous experiments with kites. By flying a
negative to describe charges. He also proved kite in a thunderstorm, he was able to pro-
in a classic experiment that lightning is duce sparks from the end of the wet string,
electrical in nature and went on to invent which he held with a piece of insulating
the lightning rod. In addition to being a silk. The lightning rod used everywhere
scientist and inventor, Franklin is widely today owes its origin to these experiments.
remembered as a statesman. He played a Furthermore, some of Franklin’s last work
leading role in drafting the Declaration of in this area demonstrated that while most
Independence and the Constitution of the thunderclouds have negative charges, a
United States. few are positive—something confirmed in
Franklin was born in Boston, Massa- modern times.
chusetts, of British settlers on January 17, Franklin also busied himself with such
1706. He started life with little formal diverse topics as the first public library,
instruction, and by the age of 10, he was bifocal lenses, population control, the rock-
helping his father in the tallow and soap ing chair, and daylight-saving time.
business. Soon, apprenticed to his brother, Benjamin Franklin is arguably the most
a printer, he was launched into that trade, great success and brought Franklin a consid- interesting figure in the history of science and
leaving home in 1724 to set himself up as a erable income. not only because of his extraordinary range
printer in Philadelphia. His business pros- In 1746, his business booming, Frank- of interests, his central role in the establish-
pered, and he was soon active in journalism lin turned his thoughts to electricity and ment of the United States, and his amazing
and publishing. He started the Pennsylvania spent the next seven years executing a willingness to risk his life to perform a cru-
Gazette but is better remembered for Poor remarkable series of experiments. Although cial experiment—a unique achievement in
Richard’s Almanac. The almanac was a col- he had little formal education, his voracious science. By conceiving of the fundamental
lection of articles and advice on a huge range reading habits gave him the necessary back- nature of electricity, he began the process by
of topics, “conveying instruction among the ground, and his practical skills, together which a most detailed understanding of the
common people.” Published in 1732, it was a with an analytical yet intuitive approach, structure of matter has been achieved.

Source: Modified from the Hutchinson Dictionary of Scientific Biography © Research Machines 2008. All rights reserved. Helicon Publishing is a division of Research Machines.

An electric utility charges you for the electrical power used
at a rate of cents per kilowatt-hour (typically 5–15 cents/kWh). TABLE 6.2

The rate varies from place to place across the country, depend-
Summary of electrical quantities and units
ing on the cost of producing the power. You can predict the cost
of running a particular electric appliance with the following Quantity Definition* Units
equation.
Charge q = ne coulomb (C) = charge
(watts)(time)(rate)
__ equivalent to 6.24 × 10 18

cost = _ particles such as the electron

1,000 watts Electric
kilowatt W _ __
joule (J)

potential V = volt (V) = coulomb (C)
q
equation 6.7 difference
coulomb (C)
_
Electric q amp (A) = __

If the watt power rating is not given, it can be obtained by mul- current I = second (s)
t
tiplying amps by volts. Also, since the time unit is in hours, the Electrical V _ _
volt (V)

time must be converted to the decimal equivalent of an hour if resistance R = ohm (Ω) = amp (A)
I
you want to know the cost of running an appliance for a number Electrical __
joule (J)
of minutes (x min/60 min). power P = IV watt (W) = second (s)
Table 6.2 provides a summary of the electrical quantities
and units. *See Summary of Equations for more information.
6-15 CHAPTER 6 Electricity 153