The Physics Factbook™
Edited by Glenn Elert -- Written by his students
An educational, Fair Use website
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|Cutnell, John D., Johnson, Kenneth W. Physics. 4th ed. New York, NY: Wiley, 1998.||"Currents of approximately 0.2 A are potentially fatal, because they can make the heart fibrillate, or beat in an uncontrolled manner."||0.2 A|
|Carr, Joseph J. Safety for electronic hobbyists. Popular Electronics. October 1997. as found in Britannica.com.||"In general, for limb-contact electrical shocks, accepted rules of thumb are: 1-5 mA is the level of perception; 10 mA is the level where pain is sensed; at 100 mA severe muscular contraction occurs, and at 100-300 mA electrocution occurs."||0.1–0.3 A|
|"Electrical Injuries." The Merck Manual of Medical Information: Home Edition. Pennsylvania: Merck, 1997.||"At currents as low as 60 to 100 milliamperes, low-voltage (110-220 volts), 60-hertz alternating current traveling through the chest for a split second can cause life-threatening irregular heart rhythms. About 300-500 milliamperes of direct current is needed to have the same effect."||0.06–0.1 A
|Zitzewitz, Paul W., Neff, Robert F. Merrill Physics, Principles and Problems. New York: Glencoe McGraw-Hill, 1995.||"The damage caused by electric shock depends on the current flowing through the body -- 1 mA can be felt; 5 mA is painful. Above 15 mA, a person loses muscle control, and 70 mA can be fatal."||0.07 A|
|Watson, George. SCEN 103 Class 12. University of Delaware. March 8, 1999.||"0.10 death due to fibrillation
> 0.20 no fibrillation, but severe burning, no breathing"
|Miller, Rex. Industrial Electricity Handbook. Peoria, IL: Chas. A. Bennet, 1993.||"Currents between 100 and 200 mA are lethal."||0.1–0.2 A|
A common misconception is that larger voltages are more dangerous than smaller ones. However, this is not quite true. The danger to living things comes not from the potential difference, but rather the current flowing between two points. The reason that people may believe this can be explained by the equation V = IR. Since V is directly proportional to I, an increase in voltage can mean an increase in current, if resistance (R) is kept constant.
The amount of damage done by the electric shock depends not only on the magnitude of the current, but it also on which portions of the body that the electric current is flowing through. The reason for this is that different parts of the body have difference resistances, which can lead to an increase in current, evidenced by the formula V = IR.
An interesting fact to note is that it takes less alternating current (AC) to do the same damage as direct current (DC). AC will cause muscles to contract, and if the current were high enough, one would not be able to let go of whatever is causing the current coursing through the body. The cut-off value for this is known as the "let-go current". For women, it is typically 5 to 7 milliamperes, and for men, typically 7 to 9 milliamperes. This is dependent on the muscle mass of the individual.
In general, current that is fatal to humans ranges from 0.06 A to 0.07 A, depending on the person and the type of current.
Jack Hsu -- 2000
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