| Electricity is one of the foundations of our world: our | | | | The simplest way to think of the number of volts is |
| modern way of life would grind to a halt were there | | | | as the amount of desire electrons in the current have |
| no electricity to run our myriad of gizmos and | | | | to get across the distance separating the differently |
| gadgets. As such, an entire field of engineering | | | | charged regions. That is, the "voltage," or potential |
| dedicated to keeping the juice flowing and finding | | | | difference, across a gap of a given distance varies |
| ways of using that power to do all sorts of | | | | with the amount of the difference in charge from |
| interesting things has developed. Most of us, | | | | one side of the gap to the other. If one side of the |
| however, are content just to know that if you plug | | | | gap has five units of positive charge and the other |
| your TV into the wall outlet and press the power | | | | side five units of negative charge, the voltage will be |
| button, you can watch your favorite diversions to | | | | five times greater across the gap than if there were |
| your heart's content. This article will sort out the | | | | one unit of positive or negative charge on each |
| mysteries of volts, amps, watts, and other concepts | | | | respective side. |
| in electricity. | | | | The watt (named after Scottish inventor and |
| How important is electricity? Without it, the monitor | | | | engineer James Watt), finally, is a unit of power, just |
| with which you are viewing this article right now | | | | like the horsepower is a unit of power. Since power |
| would not work, nor would the CPU which decodes | | | | is the same quantity in the eyes of physics whether |
| this web page and tells your monitor what to display. | | | | it comes in the form of electrical power or |
| Given the importance of computing and the internet | | | | mechanical power or any other form of power, |
| email in the worlds of business, finance, science, and | | | | nothing about the watt is particular to electricity. |
| daily life, this alone is a rather important reason to | | | | Now what is "power," you ask? A physicist defines |
| ensure that the juice keeps flowing. | | | | power as the amount of work done (or the amount |
| Besides its role in the recent computer and internet | | | | of energy used) in a certain amount of time. Imagine |
| revolution, electricity plays a vital role in modern | | | | two cars, a typical family sedan and a high-powered |
| industry, whether to power industrial robots or to | | | | racing car, each given the same amount of the same |
| harness the raw power of huge electrical currents to | | | | type of fuel. The amount of fuel in the tank is the |
| melt iron in steel foundries. | | | | energy reserve a car has available, and since each |
| So, just what is electricity? The basic definition is | | | | car has the same amount of the same fuel, each can |
| quite simple to understand: electricity is a flow of | | | | theoretically travel exactly the same distance before |
| electric charge. Charge is a fundamental quantity in | | | | running out of fuel and rolling to a stop (assuming |
| physics (i.e., it cannot be described in terms of yet | | | | equal mass and the same conditions for each car). If |
| more basic concepts) which all of the fundamental | | | | both cars are cranked to their maximum output, |
| subatomic particles which make up our world carry | | | | however, the regular sedan may take twice as long |
| (neutrons are not fundamental particles but are made | | | | as the race car before it finally rolls to a halt beside |
| from charged particles whose charges happen to | | | | its sexier counterpart, in which case we would say it |
| cancel). | | | | has half the power of the race car (but equal |
| The amp, short for ampere (named after eighteenth | | | | energy). |
| century French physicist Andre-Marie Ampere) is the | | | | In electricity, it turns out that power is the product |
| basic unit of electric current. Electric current is quite | | | | of current and voltage. Thus, multiplying the potential |
| analogous to a flow of water: the amount of "stuff" | | | | difference (in volts) in a wire by the current (in |
| that goes past a point in a certain time is the current | | | | amps) gives you the power coursing though the |
| at that point. In the case of water, or any other | | | | wire, in watts. Since voltage and current can be |
| fluid, engineers use a term called volume flow rate, | | | | interchanged to give the same power output, |
| which is the volume of said fluid that passes through | | | | transformers are used to achieve the optimal |
| a certain cross-sectional area per unit of time (e.g., X | | | | trade-off between current and voltage in power |
| cubic meters per second). The definition of electric | | | | transmission lines. In this case, the lowest possible |
| current is similar, except that the "stuff" being | | | | current is optimal since higher currents demand |
| measured is the amount of electric charge passing | | | | thicker wires and create more heat, so the voltage is |
| through an area such as a point on a wire. | | | | stepped up to very high levels in power lines and |
| Voltage, on the other hand, is a somewhat trickier | | | | then stepped down to regular line voltage at the |
| concept to put into familiar terms. What we call | | | | power station for distribution to local users. |
| "voltage" is actually an informal reference to electric | | | | While it may seem simple to plug in a TV and "zone |
| potential difference (no wonder we find it easier to | | | | out in front of the 'tube," there is reason to |
| say "voltage" instead!). The closest analogy to a flow | | | | understand the basics of electricity. The world is not |
| of water is to the pressure difference in a pipe; | | | | as simple as it may seem, because each appliance or |
| absent any greater momentum in the opposite | | | | cell phone or laptop computer is designed to run on a |
| direction, water will flow from the area of greatest | | | | different line voltage, at a different current, for a |
| pressure to the area of least pressure. While | | | | different power rating. Feeding a part less power |
| pressure creates a "potential" in the case of water, it | | | | than it needs would be relatively harmless, but doing |
| is a difference in charge which creates this potential | | | | the opposite can destroy that device you shelled out |
| in the case of electricity: a current is simply nature's | | | | hard earned money for! With the information |
| way of trying to even out an imbalance of charge by | | | | presented here in mind, you may now know what a |
| sending negative charges to an area where there is a | | | | user guide means when it specifies power |
| relative deficiency of negative charge (i.e. a more | | | | requirements for a part, and hopefully this will make |
| positively charged region), or vice versa. | | | | your life easier. |
| A "volt," then, is a unit of electric potential difference. | | | | |