You will need to know some basic information about electricity and how it works for the Electronics Information subtest of the ASVAB. One day in 1752, Benjamin Franklin was minding his own business, flying a kite in a storm. A key was tied to the kite string and when lightning struck the metal key, Ben was struck by the notion that lightning must be electrified air (well, it happened something like that).

Although electricity was just a hobby for Ben Franklin, he made many important contributions. As a result of his famous kite flight, he created many of the terms used today when folks talk about electricity: battery, conductor, condenser, charge, discharge, uncharged, negative, minus, plus, electric shock, and electrician.

*Electricity* is a general term for the variety of phenomena resulting from the presence and flow of electric current. You can’t see electricity running through a wire (but you can certainly feel it). You only know electricity is there when you flip on the light switch and the light turns on. Even though electricity appears to be pretty mysterious at first glance, scientists understand a great deal about its properties and how it works.

Electricity is measured in three ways:

**Volts:**Volts measure the difference of potential between two points.**Amperes (amps):**Amps measure the number of electrons that move past a specific point in 1 second.**Ohms:**Ohms measure resistance, including anything that could limit the flow of electrons.

Here are some other electricity terms that are important for you to know for the ASVAB:

**Current:**Electricity is like water — it flows. Electrical current occurs when electrons move from one place to another. The use of*conductors,*such as copper and water, allows the electrons to move freely.*Insulators,*such as rubber and wood, discourage the electric current.**Watt:**A watt measures*power,*the rate at which electrical energy is consumed or transformed into another type of energy, such as light or heat.**Watt-hour:**A watt-hour is the amount of energy used in 1 hour at a rate of 1 watt. Most electricity is measured in kilowatt-hours, which is how much energy you’d use if you ran a 1,000-watt (1-kilowatt) device for an hour.For example, 10 kilowatt-hours is enough energy to run a 10,000-watt speaker system for an hour-long outdoor concert, or it could run a 5,000-watt air conditioner for 2 hours or a 1,000-watt waffle iron for 10 hours. You find watt-hours by multiplying wattage by time (expressed in hours).