Nature and Effects of Electricity

The meaning of the word "Electricity"

Electricity is a term that covers all the phenomena caused either by static electric charge or by the movement of charge (current) and the electrical and magnetic fields associated with that. Electricity is commonly understood to be a form of energy comparable to other energy forms such as heat, light, mechanical or chemical energy. Electrical energy has some major advantages over other forms of energy, however:

Electrical energy can be easily conveyed over long distances. Power stations supply large areas via overhead transmission cables. 
Electrical energy can easily be converted into other forms of energy, e.g. heat, light or mechanical energy. It is therefore used commonly both domestically and in industry.


Natural Electrical Phenomena

Probably the best known and most spectacular appearance of electricity is in the form of lightning. Lightning involves a discharge of high electrostatic voltages generated by friction between storm clouds. Such a discharge involves the motion of both positive and negative charges. Electricity also occurs in less obvious forms, however. For example, the transmission of information through the human nervous system is partially based on electrical signals. Certain types of fish like the electric eel (bottom right) can also generate high voltages for the purpose of defence. They can also detect electrical signals generated by the muscle movement of other fish and use these to locate prey.



Effects of Electricity on the Human Body

Electricity can have a variety of effects on the human body depending on its strength. The decisive factor in terms of its effect on the body is the current. Low currents are sometimes used to accelerate healing processes in a technique known as electrotherapy, or can provide pulse signals for a cardiac pacemaker. Larger currents may even revive a heart that has stopped beating when applied with a so-called defibrillator (pictured right). Higher currents in excess of abut 50 mA can be dangerous and even deadly. An electric shock stun gun, for example, shoots a series of powerful electrical signals through a victim that cause painful, uncontrollable muscle spasms. At the extreme end of the scale, very high current may be intentionally used to kill, as in the case of the electric chair. effects-electricity-human-body.jpg

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