Electric Shock....!

try this for an answer

Burns

Heating due to resistance can cause extensive and deep burns. Voltage levels of 500 to 1000 volts tend to cause internal burns due to the large energy (which is proportional to the duration multiplied by the square of the voltage divided by resistance) available from the source. Damage due to current is through tissue heating. It is a relatively unknown fact that more electrical workers die from burns than from an electric shock. In fact, only around 20% of deaths are the result of electric shock.[5]

[edit]Ventricular fibrillation

A domestic power supply voltage (110 or 230 V), 50 or 60 Hz AC current through the chest for a fraction of a second may induce ventricular fibrillation at currents as low as 60 mA. With DC, 300 to 500 mA is required.[2] If the current has a direct pathway to the heart (e.g., via a cardiac catheter or other kind of electrode), a much lower current of less than 1 mA (AC or DC) can cause fibrillation. If not immediately treated by defibrillation, fibrillations are usually lethal because all the heart muscle cells move independently instead of in the coordinated pulses needed to pump blood to maintain circulation. Above 200 mA, muscle contractions are so strong that the heart muscles cannot move at all.

[edit]Neurological effects

Current can cause interference with nervous control, especially over the heart and lungs. Repeated or severe electric shock which does not lead to death has been shown to cause neuropathy. Recent research has found that functional differences in neural activation during spatial working memory and implicit learning oculomotor tasks have been identified in electrical shock victims.[6] When the current path is through the head, it appears that, with sufficient current[clarification needed], loss of consciousness almost always occurs swiftly. (This is borne out by some limited self-experimentation by early designers of the electric chair[citation needed] and by research from the field of animal husbandry, where electric stunning has been extensively studied.)[7]

[edit]Arc-flash hazards

One major corporation[which?] found that up to 80 percent of its electrical injuries involve thermal burns due to arcing faults.[8] The arc flash in an electrical fault produces the same type of light radiation from which electric welders protect themselves using face shields with dark glass, heavy leather gloves, and full-coverage clothing.[9] The heat produced may cause severe burns, especially on unprotected flesh. The blast produced by vaporizing metallic components can break bones and irreparably damage internal organs. The degree of hazard present at a particular location can be determined by a detailed analysis of the electrical system, and appropriate protection worn if the electrical work must be performed with the electricity on.

[edit]Pathophysiology

[edit]Body resistance

The voltage necessary for electrocution depends on the current through the body and the duration of the current. Ohm's law states that the current drawn depends on the resistance of the body. The resistance of human skin varies from person to person and fluctuates between different times of day. The NIOSH states "Under dry conditions, the resistance offered by the human body may be as high as 100,000 Ohms. Wet or broken skin may drop the body's resistance to 1,000 Ohms," adding that "high-voltage electrical energy quickly breaks down human skin, reducing the human body's resistance to 500 Ohms."[10]

The International Electrotechnical Commission gives the following values for the total body impedance of a hand to hand circuit for dry skin, large contact areas, 50 Hz AC currents (the columns contain the distribution of the impedance in the population percentile; for example at 100 V 50% of the population had an impedance of 1875Ω or less):[11]

Voltage 5% 50% 95%

25 V 1,750 Ω 3,250 Ω 6,100 Ω

100 V 1,200 Ω 1,875 Ω 3,200 Ω

220 V 1,000 Ω 1,350 Ω 2,125 Ω

1000 V 700 Ω 1,050 Ω 1,500 Ω

[edit]Point of entry

Macroshock: Current across intact skin and through the body. Current from arm to arm, or between an arm and a foot, is likely to traverse the heart, therefore it is much more dangerous than current between a leg and the ground. This type of shock by definition must pass into the body through the skin.

Microshock:

Very small, current source with a pathway directly connected to the heart tissue. The shock is required to be administered from inside the skin, directly to the heart i.e. a pacemaker lead, or a guide wire, conductive catheter etc. connected to a source of current. This is a largely theoretical hazard as modern devices used in these situations include protections against such currents.

[edit]Lethality

This section may contain original research. Please improve it by verifying the claims made and adding references. Statements consisting only of original research may be removed. More details may be available on the talk page. (December 2010) The lethality of an electric shock is dependent on several variables:

1) Current (the higher the current, the more likely it is lethal)

2) Duration (the longer the duration, the more likely it is lethal - safety switches limit time of current flow)

3) Pathway (if current flows through the heart muscle, it is more likely to be lethal)

4) Voltage

Other issues affecting lethality are frequency, which is an issue in causing cardiac arrest or muscular spasms, and pathway-if the current passes through the chest or head there is an increased chance of death. From a main circuit or power distribution panel the damage is more likely to be internal, leading to cardiac arrest.[citation needed].

The comparison between the dangers of alternating current and direct current has been a subject of debate ever since the War of Currents in the 1880s. It is sometimes suggested that human lethality is most common with alternating current at 100-250 volts; however, death has occurred below this range, with supplies as low as 32 volts. Shocks above 2700 volts are often fatal, with those above 11000 volts being usually fatal.[citation needed] Shocks with voltages over 40,000 volts are almost invariably fatal. However, Harry F. Mcgrew came into direct contact with a 340,000 volt transmission line in Huntington Canyon, Utah, and survived. According to the Guinness Book of World Records, this is the largest known electric shock that was survived. Brian Latasa also survived a 230,000 volt shock in Griffith Park, Los Angeles, according to Guinness.

[edit]Epidemiology There were 550 electrocutions in the US in 1993, which translates to 2.1 deaths per million inhabitants. At that time, the incidence of electrocutions was decreasing.[12] Electrocutions in the workplace make up the majority of these fatalities. From 1980-1992, an average of 411 workers were killed each year by electrocution.[10]

Ok, I thought you were asking this. (Don't worry about the language barrier, your English is much better than my Hindu. As long as you ask relevant questions about what you do not understand, I'll work to cross the barrier.)

Lets not worry about how heat happens in the human body from electrocution, let's first just focus on how heat happens from current flow alone. To grasp all of the aspects about how current produces heat you really need a little understanding of Physics, Material Science and Chemistry.

I hope that you remember the Bohr atom model and the atomic definition of temperature. First allow me a relevant review of the Bohr atom. A cloud of negatively charged electrons exist in orbitals around the positively charged nucleus. There is much more to this model but a few critical things to keep in mind here is that a balance in the number of positive and negative charges keeps the atom at a neutral charge and that virtually all of the mass of the atom exists in the nucleus.

Now the atomic model of the temperature of material is that the temperature is average vibrational energy of each atom. If the average energy is below a critical value then all of the atoms are locked into place (but wiggling in that place) and you have a solid. If the energy is high enough that the atoms can move past each other but do not have enough energy to escape each other, then this is a liquid. Lastly if the average energy is high enough that the atoms can escape any mutual attraction of atom to atom then you have a gas.

Lastly of my introduction is the Chemistry of conduction versus insulation. The pivotal concern of Chemistry is the electrons that are easiest to remove of an atom orbital, known as the valence electrons. The noble gasses do not have any electrons that are easy to remove nor do they have any unfilled orbitals. Metals have a few electrons that are relatively easy to remove in the valence orbital while also having a full orbital of electrons that will not be removed easily. Non-metals almost have a full collection of electrons in the valence orbital while also having orbitals that are fully occupied.

Now that I've laid the relevant foundation, let me discuss how conduction occurs in a metal. When an electrostatic field gets applied to a metal atom, the valence electrons of the metal get attracted to the positive terminal of the electrostatic field. If the E field is sufficiently high a metal ion is created when the first electron gets stripped off. (To strip off a second electron now requires a considerably higher E field because the atom is no longer neutrally charged.) The metal ion will now be accelerated away from the positive terminal. Now if a closed loop of metal atoms exist across the E field then instead of metal ions being formed a series of electron sharing happens where one atom provides the next atom a replacement electron. However, because the metal atoms vibrate from their temperature the distance between atoms is not exactly the same at every tiny instant in time. Therefore brief momentary metal ions happen that get moved briefly. This brief atomic acceleration is the added heat generated in the conductor.

Now a few more bits must be added to explain how resistances (flesh) differ from metals and what makes an insulator. When a molecule consists of atoms that are sharing their electrons so that only complete orbitals exist then the only way electrons can be dislodged from an orbital will be to ionize the molecule. (Not 100% accurate but the principle for this discussion is true.) These molecules will not support the chain condition I mentioned above and thus an open circuit condition will exist. This is why metal oxides are insulators. Now most metal oxides are only one or two atoms thick on a metal so often wiping contacts or just the applied voltage is sufficient to break through the oxide. Gold does not produce oxides easily. This is why many contacts are gold plated. The semi-conductor elements (Carbon, Silicon, Germanium) and molecules have in there valence shell half the number of electrons to complete an orbital. So they can complete a circuit but it takes much more of an effort applied to the atom to get them to transfer electrons. Thus more force gets applied to the whole atom and thus more heating happens with these elements.

There's much more to this phenomena, specifically the dipole moment of water, that goes into how current produces heat in flesh. But this alone is a lot to absorb if you've never heard any of this before.