... that was the conclusion I got into classes electromagnetism. It seemed funny for obvious reasons and is an interesting way to address an issue that has nothing intuitive but is in all aspects of our lives: electricity and related phenomena.
I think it is remarkable how in a little over 2000 years we have improved our quality of life with inventions generated from systematic observation of nature. One such area is the power of observation. It is an intrinsic property of elementary particles is the electric charge. The burden is known owner: like charges repel and opposite charges attract. This property is the reason why we can walk, sit in chairs and the reason why close the legs during a lightning storm reduces the chances of being stuck by lightning. Tear those 2 statements. The arc to reach the explanation is a little broad, I ask a little patience.
to talk about it is necessary to make certain words. Most of these terms have their formal counterparts (a mathematical model or an argument based on basic principles and observation). The version here is treated without mathematics and examples abound.
Some of the known matter is formed more or less the same materials: electrons, protons and neutrons. In the compositions of these fundamental ball we call atoms. Naturally, there will be atoms that are formed by different combinations. For that we invent a useful convention that classifies the atoms to the number of balls that have (atomic). Most of these atoms have different combinations with similar properties. These variants are called isotopes . Example: There are different combinations of elementary particles that form a carbon atom. One of them is carbon 14. Carbon 14 is an isotope of carbon.
So using the fact of all materials that interact consist of the same materials: what happens when you grab a pen in hand?
atoms pencil our fingers and have electrons that are close enough to feel repulsion between them (equal negative charges). These small repulsive forces occur by the millions and go in all directions. The sum of these forces is called friction in the macroscopic world of human fingers and pencils. If there were the electric repulsion, friction would not and could not use tools, walking, eating, etc..
So what happens when we sit down? Our electrons and chair repel each other until your weight is balanced. Literally, we are floating and friction is what keeps floating out of the chair.
continue with the second statement.
Among the atoms there are some that call metals. The properties of metals are known to all and are interested in one in particular: electrical resistance. Among the isotopes of an atom is an unstable manifold is always giving away balls or stealing their neighboring atoms. These atoms are called ions . Are positive when they lose electrons and negative when they gain electrons from neighboring atoms. The words positive and negative are not related to its other meaning (good / bad). That is, only used to differentiate and emphasize that they have a kind of symmetry. In some alternative medicine practices (the vitamin and purifiers, for example), a negative ion (or free radical) is perceived as harmful to the body. This is totally absurd. All matter has a random soup of stable atoms and ions, are part of our body: thus we are made. Now we know that the word refers to a negative electrical property of a particular atom. Follow.
Returning to the concept of electrical resistance, and using new words entered, a metal atom is a compound that has a high proportion of ions ( driver). The presence of these unstable atoms makes the electrons jump from atom to atom. It is said that a material with this property has a low electrical resistance. We monkeys, curious we are, we learned to interact with these loose electrons in metals and develop an area called electronics. The electronics and appliances turn on this property of matter (and some others not mentioned here for not sacrificing readability.)
Another property that is necessary to introduce is one that is a bit complicated to explain because it is used colloquially constamente: voltage or electrical potential difference . Think in 2 metal bars charged negatively and positively (ie, one has more electrons and the other is missing). Now connect the two bars with a wire conductor (remember that the driver is the one metal that has the ability to conduct electrons "loose" through it). When the wire touches the positive rail, the electrons loose wire going to want to move the bar (opposite charges attract.) At the same time the negative bar is replacing the wire electrons gave to the positive rail. This process continues until both rods and wire are the same load. This "sharing electrons" is known as power. Notice how in both examples, the 3 components end with the same load. A nature pleases balance (for very interesting that out of range of this discussion).
What if instead of a wire put a focus between the bars? Repeat the process. The electrons leave the negative rod, enter the cable, some are used by the focus mechanism to generate light and go left over the positive rail. The focus is off when both bars have the same charge, as in the example above. If we now add a source of electrons to negative rod fill their cargo, we have a battery . Batteries extract electrons from an acid and plates of different metals to make the process continuous. Open your mind please ... 
In fact bring the bar is known as establishing a potential difference . Ie between the positive and negative bar there is a voltage (or a potential difference) that facilitates the movement of electrons through a conductor located between both bars. The driver may be a wire, a bulb or a huge collection of circuits (like a computer). The principle is the same for all. This potential difference depends on the distance between the bars. The closer they are, their potential difference is closer to zero. Here's a left fork for those interested: how much can I bring the bars before producing a spark or electrical discharge between them (ie the air then the conductor cable)? Investigate "breakdown voltage" or "breakdown voltage".
With this we have enough tools to better understand the second statement. Imagine a rainstorm in slow motion. If lightning strikes close to us, the electron beam in a radial dissipate over land (forming larger and larger circles). When the first circle touches one of our legs, it is electrically charged while the other leg remains with its original charge. This satisfies the need to establish a potential difference, thereby creating electricity. Our body acts as a conducting wire connecting our legs and produces a current. Keep your legs closed reduces the potential difference between them, while reducing the probability of power dissipated by lightning during a storm.
Another conclusion that can be useful to eliminate certain defects of language: a high potential difference (HV) is not dangerous by itself. Is the current that can be generated which carries the risk. say "Danger: High Voltage" equivalent to "Danger: Open sky, you can drop a plane on the head" . "Danger: possible electric shock" is much more accurate.
Electricity is a very broad and very interesting. Has been developed, formally, from the 1700's (if not much earlier) and saw a tremendous step forward from the work of several scientists, including: James Clerk Maxwell . A remarkable kind; full academic. I think it's more than enough to mention the role of such significance that this discovery has on our lives. Electricity is our friend and will be for another long while. However, new technology aimed in another direction. Perhaps our generation will not see the obsolete electronics, but if the commercial introduction of technologies [relatively] recent as quantum computing or photonics . In fact, there are already domestic applications related to photonics (fiber-optic telecommunications). Whenever there is a possibility to explode, there will be someone interested, is a basic result of curiosity. Without doubt, a useful feature for the survival of any species.
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