# Electricity Unit Summary

## So, what have we learned in this unit?

We have learned that all matter is composed of atoms and that atoms are composed of protons, neutrons, and electrons. Protons have a positive charge, neutrons have a neutral charge, and electrons have a negative charge. Some materials, like copper, have electrons that are loosely held by their atoms and these "free" electrons easily move from atom to atom. Normally, these free electrons are moving from atom to atom in random directions so there is no net movement of electrons on one direction. However, we can force the electrons to move in on direction using a magnetic field, chemical reaction or other means. Electricity is the directional flow of electrons.

The directional flow of electrons (electrical current) is very useful because it can be used to do work. When electrons are moving, they produce a magnetic field and this magnetic field can be used to cause the shaft of a motor to spin and do work. Electrical current also generates heat that can be used to warm a home or produce light. The electrons moving through the filament of an incandescent light bulb cause the filament to heat up and glow. Only the fact that there is no oxygen inside the light bulb keeps the filament from burning up.

Electricity can also be used to make measurements and inspect conductive materials. When electricity is flowing in a coil, it produces a magnetic field in and around the coil. This magnetic field of the coil can then be used to generate electrical current in another conductor. These electrical currents are called eddy currents because they travel in circles like eddy currents in a stream. The strength of the eddy currents can be measured and this provides useful information about the material.

In this unit, we also learned about the various measures that are used to quantify electricity. Amperage is a measure of the electrical current strength and is the number of electrons moving past a fixed point in one second. Voltage is a measure of how many electrons are present in one area compared to another. When there is an imbalance of charge, the electrons want to move to the area of lower concentration until equilibrium is reached. The imbalance of charge is called electromotive force and it is measured using the volt as the unit.

You should also be aware that electricity can be very dangerous.  Electricity can cause burns and interfere with the normal electrical signals of the body and cause the heart to beat irregularly or even stop beating.  So, use electricity wisely and with caution.

Electricity is just one of the forms of energy that are useful to society.  Return the main menu and learn about one of the other energy forms discussed on this website.