# Why is electric current dangerous to humans? [closed]

How does a strong electric current harm our body? A strong electric current will posses a great charge. But how does that charge injure us?

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## closed as off-topic by jinawee, Brandon Enright, DavePhD, Kyle Oman, Kyle KanosJun 10 '14 at 0:24

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This question appears to be off-topic because it is about physiology (and could be answered with a Google search). –  jinawee Jun 9 '14 at 19:33

High-power electric currents cause burns due to Ohmic heating: your body resists the flow of the current, and so the current flow deposits heat. The burns may be internal as well as external.

High-voltage current arcs (sparks) can make air a conducting plasma, which allows the arc to continue to heat the air, which allows more current to flow, etc. This can produce an explosion called an arc blast which may involve spraying molten metal. The threshold for this is surprisingly low — it's a slight hazard when throwing a 440 V circuit breaker.

Alternating currents can interfere with neuron-to-neuron signaling, causing nasty things like cardiac fibrillation, where the heart muscles lose synchronization and the heart wiggles instead of pumping. By an unfortunate coincidence the frequencies we use for power distribution (50–60 Hz) are especially efficient at stopping hearts, even at fairly low currents.

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@Harry: yes, heat. The water in the body has a lot of ions in it, so it is a mildly conductor. The electricity will flow from one cell to another, and they will be heated in the process: $P = I^2 R$. If the current is high enough the cells will literally boil. –  rodrigo Jun 9 '14 at 14:47