HOW COME? Human body a conductor for electricity

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Why do we get shocked when we come in contact with electricity? asks reader Sangpal Meshram.

Don't touch an electrical outlet with wet hands. Keep hair dryers away from sinks and bathtubs. And never, ever put your metal fork in a toaster to unstick the toast.

Why all the warnings? Blame teeny-tiny electrons, freewheeling through a copper wire.

Like all matter, the copper wire running to the outlets in your house is made of atoms. Atoms have a center (nucleus) made of particles called protons and neutrons. Neutrons aren't electrically charged. But protons are, and their charge is positive.

The positive protons keep electrons, which are negatively charged, swarming around the nucleus in a kind of cloud. Opposites, after all, attract. Each regular copper atom has 29 electrons orbiting its nucleus. And millions upon millions of copper atoms make up even a short length of copper wire.

Why copper? In metals like copper (or aluminum), electrons can easily escape the hold of the nucleus and wander like nomads from atom to atom. When a wire is connected to a working electric circuit, the copper atoms' footloose electrons begin to drift in a particular direction. Presto: an electric current.

Here comes the shocking part: That stream of electrons, jumping from atom to atom, can also leap from toaster wires to fork to hand. Why? Like copper and other metals, the human body is also a good conductor.

Ordinary water, which contains dissolved minerals and salts, conducts electricity, too. Which is why lifeguards order everyone out of the pool when storm clouds gather, lightning flashes and thunder booms.

Materials that don't have wandering electrons are called electrical insulators. We can safely touch a switched-on lamp's cord because the wire inside is insulated by the plastic around it.

Good insulators, which don't have wandering electrons, include glass, plastic, and rubber.

So touch the outside of a wall outlet with dry hands and you're unlikely to get shocked, since your skin won't make contact with wiring in the wall. But if your hands are wet, water can slip into the outlet. Current can flow through the water and into your wet hand. The result is a painful -- or dangerous -- shock.

What causes the feeling of a mild shock? The body runs on its own electricity, and tiny currents power our muscles. The muscles in your hand react to the intruding current by contracting, creating a twitchy, buzzing feeling.

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