在干燥的季節，當我們的手碰觸到金屬、電線或是另一個人的身體，就會感到有股電流迅速流過我們的身體，伴隨著“啪”的一聲：被電到了。大家都知道干燥的季節容易起電，那為什么我們人類會這么容易被電到呢？

    Electricity shocks us, because it is an outside force that interferes with the internal electricity our bodies' nervous systems generate. 

    To fully understand why the chance encounter of these two electrical forces results in a shock to our systems, we must first understand the fundamentals of electricity itself. 

    In scientific terms, electricity is considered a fundamental force, one that is extremely basic, and has been in existence since the beginning of time. Further simplified, it is so basic, that it defies explanation, and is Mother Nature's way of saying "Because I said so"! 

    Electricity comprises positive and negative charges, opposite charges attract each other, and similar charges repel each other. Those charges attracted to each other can be separated, with the end product being potential energy, that is, energy that will be released as voltage, should the two reunite. We pay electric companies to separate the positive and negative charges for us, so that we have electrical energy at our disposal.
In order for the charges to reunite, and for the potential energy to be released as voltage, a conductor, a channel that they can flow through, is needed. Insulators, such as paper and glass make poor conductors, while wire and water make excellent conductors. Unfortunately, since the human body consists primarily of water, it too provides a superb conductor for electrical energy, or voltage. 

    If, by chance, outside electrical energy enters our bodies, now conductors, we will be shocked when the voltage encounters, and interferes with, the internal electrical energy our nervous systems produce. The shocks to our bodies, and the amount of damage the electricity does to them, depends upon the voltage our bodies are subjected to, upon its level of energy, and upon how much our bodies resist the flow of the electrical energy. 

    When we are shocked, a variety of things may occur, none of which is desirable. Our muscles may twitch, we may experience problems in the nerve centers that control our breathing, or we may experience problems with our heart rhythms. The worst case scenario from being shocked is death. 

    voltage: 電壓，伏特數 

    conductor: 導體

    insulator: 絕緣體