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Electronics Information for Armed Services Vocational Aptitude Battery (ASVAB) Study Guide

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Updated on Jul 5, 2011

SUMMARY

We use electricity every day of our lives. Light bulbs produce light from electricity. Many ovens use electricity to produce heat. Our televisions and computers use electricity. Our cars use electricity to ignite the fuel in the engine. Batteries produce electricity to power games and calculators. This article will add to your knowledge of electronics and review what you already know so that you can get a top score on the Electronics Information subtest of the ASVAB.

The electricity used in the United States is predominately produced from three resources: fossil fuels, such as oil, natural gas, and coal; nuclear materials, primarily uranium; and hydropower from water.

Almost 80 percent of the electrical power used in the United States is produced from the burning of fossil fuels. Fossil fuels are burned to produce heat. The heat is used to produce steam that turns a turbine. The turbine transforms rotational mechanical energy into electric energy which in turn is fed into a power grid.

Nuclear power plants produce about 7 percent of the electricity we consume. A nuclear power plant uses a nuclear reaction (fission) to produce heat that generates steam. The process described above is then used to convert steam into electricity.

About 15 percent of the electricity we use is from hydropower. The kinetic energy of falling water is used to turn turbines that produce the electrical power.

Kinetic Energy: the energy produced by a body in motion.

Basic Electrical Theory

Understanding electricity and electronics is not dependent on understanding the complex structure of the atom—understanding the basics is sufficient. All materials on Earth are made up of atoms. An atom is made up in part of electrons and protons. These two subatomic particles each have an electric charge, or electric polarity. The charge of an electron has a negative polarity while the charge of a proton has a positive polarity. Electricity is essentially the management of positive and negative electric charges.

Charge

Most everyone has experienced the buildup of electric charge when shuffling across a carpet. Your body develops a static charge. It is static because the charge is not moving. When you touch a light switch, the static charge moves, creating a current. You have produced and used electricity.

The symbol for electric charge is q or Q. Charge is measured in coulombs, C. A coulomb of electrons has a negative charge and a coulomb of protons has a positive charge. A coulomb is defined as 6.25 × 1018 electrons or protons:

the charge of 6.25 × 1018 electrons = Q = 1C

Example: What is the charge, in coulombs, of one electron?

You remember that

6.25 × 1018 electrons = 1 Coulomb

To get the charge of one electron, divide both sides by 6.25 × 1018:

1 electron = .16 × 10–18 C

Voltage

An electric charge has the potential to do work by forcing another charge to move. Opposite charges attract each other and like charges repel each other, just like magnets. Thus, a positive and a negative charge would attract each other, while two negative charges would repel each other. The potential of an electric charge to do work is the voltage or the potential difference. A battery produces a voltage. This voltage can be thought of as the force that moves electrons from one terminal to the other. This force is called the electromotive force (emf). The accepted symbol for voltage is V. The schematic symbol for a DC voltage is:

Voltage

Voltage: the potential of an electric charge to do work.
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