The Physics
An encyclopedia of scientific essays

Electric Field on Earth

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Bibliographic Entry Result
(w/surrounding text)
Cutnell & Johnson. Physics.New York: Wiley, 1995: 583. "One day the electric field in the atmosphere near ground level is 110 N/C" 110 N/C
Giancoli, Douglas C. Physics, Principles with Applications. 3rd ed. Englewood Cliffs, NJ: Prentice Hall, 1991: 439. "Measurements indicate the presence of an electric field surrounding the Earth. Its magnitude is about 150 N/C at the earth's surface." 150 N/C
Handbook of Chemistry and Physics. 61 ed. Florida: CRC Press, 1980-81: F-214. "Volume element at about sea level:
E = 1.2 × 102 V/m
Volume element at about 2 km height:
E = 6.6 × 101 V/m"
120 N/C
66 N/C
Merrill Physics: Principles and Problems. New York: Glencoe, 1995: 444. "The electric field in the atmosphere is about 150 N/C, downward" 150 N/C
Landa, Judah. How to Study Physics. New York: Jay-El, 1995: 209. "Near the surface of the earth there exists an electric field whose intensity is 100 N/C directed downward" 100 N/C

The electric field is a measure of the force that is exerted per coulomb of charge. Its measure is defined as kq/r2 where k is the electrostatic constant constant, q is the amount of charge, and r is the distance between charges. The presence of an electric field is identified using a test charge.

The earth's atmosphere has an electric field that is directed radially inward. Most of my sources show that knowing the electric field of the earth can lead to the calculation of the charge on the earth's surface. Though some of the figures obtained are for the earth's atmosphere, it is true that the magnitude of the electric field outside a uniformly charged sphere is the same as if all the charge were concentrated at the center.

I obtained values for the magnitude of the electric field at the Earth's surface. These were in the range of 66 N/C to 150 N/C. These values are close enough to assume that each source received their data from a different primary source and each may be accurate in their own right. I am convinced that the figure is closer to 150 N/C than to 66 N/C because of the sources themselves.

Though the electric field is reported as being constant by some of my sources, The Handbook of Physics and Chemistry proves that the electric field intensity varies measurements taken at different altitudes above sea level. Its intensity decreases as you move farther away from the earth's surface.

Tresha Edwards -- 1998

Bibliographic Entry Result
(w/surrounding text)
Atmospheric Electricity. Grupo de Eletricidade Atmosférica (ELAT). Instituto Nacional de Pesquisas Espaciais. June 2005. "Over land the average electric field is about 120 V/m …. Assuming an exponential increase of the conductivity with altitude, it can be shown that the electric field decreases exponentially with altitude. At the 30-km level, the electric field is as low as 300 MV/m [sic]. Integrating the electric field from the earth's surface to the ionosphere gives as a result an electric potential difference of about 200 kV." 0.300–120 V/m

Editor's Supplement -- 2005