Execution by electrocution, usually performed using an electric chair, is an execution method originating in the United States in which the condemned person is strapped to a specially built wooden chair and electrocuted through electrodesplaced on the head and leg. This execution method, conceived in 1881 by a Buffalo, New York dentist named Alfred P. Southwick, was developed throughout the 1880s as a humane alternative to hanging and first used in 1890. This execution method has been used in the United States and, for a period of several decades, in the Philippines(its first use there in 1924, last in 1976).
Historically, once the condemned person was attached to the chair, various cycles (differing in voltage and duration) of alternating current would be passed through the individual's body, in order to cause fatal damage to the internal organs (including the brain). The first more powerful jolt of electric current was designed to pass through the head and cause immediate unconsciousness and brain death. The second less powerful jolt was designed to cause fatal damage to the vital organs. Death may also be caused by electrical overstimulation of the heart.
Although the electric chair has long been a symbol of the death penalty in the United States, its use is in decline due to the rise of lethal injection, which is widely believed to be a more humane method of execution. Although some states still maintain electrocution as a method of execution, today it is only maintained as a secondary method that may be chosen over lethal injection at the request of the prisoner, except in Tennessee where it may be used if the drugs for lethal injection are not available, without input from the prisoner. As of 2014, electrocution is an optional form of execution in Alabama, Florida, South Carolina and Virginia. They allow the prisoner to choose lethal injection as an alternative method. In the state of Kentucky the electric chair has been retired except for those whose capital crimes were committed prior to March 31, 1998 and who choose electrocution; inmates who do not choose electrocution and inmates who committed their crimes after the designated date are executed by lethal injection. In the state of Tennesseethe electric chair is available for use if lethal injection drugs are unavailable, or otherwise if the inmate so chooses if their capital crime was committed before 1999. The electric chair is an alternate form of execution approved for potential use in Arkansas and Oklahoma if other forms of execution are found unconstitutional in the state at the time of execution. On February 8, 2008, the NebraskaSupreme Court determined that execution by electric chair was a "cruel and unusual punishment" under the state's constitution. This brought executions of this type to an end in Nebraska, the only remaining state to retain electrocution as its sole method of execution.
INTERNET SOURCE: https://en.wikipedia.org/wiki/Electric_chair