CONTENT

  Table of Content

 Introduction    
 Chapter 1:     Energy - What Is It?
 Chapter 2:     Electricity
 Chapter 3:     Static Electricity & Resistance
 Chapter 4:     Electrical Circuits
 Chapter 5:     Stored Energy & Batteries
 Chapter 6:     Generators, Turbines and Power Plants
 Chapter 7:     Electricity Transmission System
 Chapter 8:     Fossil Fuels - Coal, Oil and Natural Gas
 Chapter 9:     Natural Gas Distribution System
 Chapter 10:     Biomass Energy
 Chapter 11:     Geothermal Energy
 Chapter 12:     Hydro Power
 Chapter 13:     Nuclear Energy - Fission and Fusion
 Chapter 14:     Ocean Energy
 Chapter 15:     Solar Energy
 Chapter 16:     Wind Energy
 Chapter 17:     Renewable vs. Nonrenewable - Environment & Air Quality
 Chapter 18:     Energy for Transportation
 Chapter 19:     Saving Energy and Energy Efficiency
 Chapter 20:     Hydrogen and Energy In Our Future
 Conclusion    

 Chapter 3: Resistance and Static Electricity
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As we have learned, some kinds of atoms contain loosely attached electrons. Electrons can be made to move easily from one atom to another. When those electrons move among the atoms of matter, a current of electricity is created.

Take a piece of wire. The electrons are passed from atom to atom, creating an electrical current from one end to the other. Electrons are very, very small. A single copper penny contains more than 10,000,000,000,000,000,000,000 (1x1022) electrons.

Electricity "flows" or moves through some things better than others do. The measurement of how well something conducts electricity is called its resistance.

Resistance in wire depends on how thick and how long it is, and what it's made of. The thickness of wire is called its gauge. The smaller the gauge, the bigger the wire. Some of the largest thicknesses of regular wire is gauge 1.

Different types of metal are used in making wire. You can have copper wire, aluminum wire, even steel wire. Each of these metals has a different resistance; how well the metal conducts electricity. The lower the resistance of a wire, the better it conducts electricity.

Copper is used in many wires because it has a lower resistance than many other metals. The wires in your walls, inside your lamps and elsewhere are usually copper.

A piece of metal can be made to act like a heater. When an electrical current occurs, the resistance causes friction and the friction causes heat. The higher the resistance, the hotter it can get. So, a coiled wire high in resistance, like the wire in a hair dryer, can be very hot.

Some things conduct electricity very poorly. These are called insulators. Rubber is a good insulator, and that's why rubber is used to cover wires in an electric cord. Glass is another good insulator. If you look at the end of a power line, you'll see that it is attached to some bumpy looking things. These are glass insulators. They keep the metal of the wires from touching the metal of the towers.
 Static Electricity
 But What Is Static Electricity?

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n various forms. One way to store it is in the form of chemical energy in a battery. When connected in a circuit, a battery can produce electricity.
Stored Energy and Batteries
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Energy cannot be created or destroyed, but it can be saved in various forms. One way to store it is in the form of chemical energy in a battery. When connected in a circuit, a battery can produce electricity.

If you look at
If you look at a battery, it will have two ends &emdash; a positive terminal and a negative terminal. If you connect the two terminals with wire, a circuit is formed. Electrons will flow through the wire and a current of electricity is produced.

Inside the battery, a reaction between the chemicals takes place. But reaction takes place only if there is a flow of electrons. Batteries can be stored for a long time and still work because the chemical process doesn't start until the electrons flow from the negative to the positive terminals through a circuit.
 How the Chemical Reaction Takes Place in a Battery

A very simple modern battery is the zinc-carbon battery, called the carbon battery for short.

This battery contains acidic material within and a rod of zinc down the center. Here's where knowing a little bit of chemistry helps.

When zinc is inserted into an acid, the acid begins to eat away at the zinc, releasing hydrogen gas and heat energy. The acid molecules break up into its components: usually hydrogen and other atoms. The process releases electrons from the Zinc atoms that combine with hydrogen ions in the acid to create the hydrogen gas.

If a rod of carbon is inserted into the acid, the acid does nothing to it.

But if you connect the carbon rod to the zinc rod with a wire, creating a circuit, electrons will begin to flow through the wire and combine with hydrogen on the carbon rod. This still releases a little bit of hydrogen gas but it makes less heat. Some of that heat energy is the energy that is flowing through the circuit.

The energy in that circuit can now light a light bulb in a flashlight or turn a small motor. Depending on the size of the battery, it can even start an automobile.

Eventually, the zinc rod is completely dissolved by the acid in the battery, and the battery can no longer be used.

For a "great" on-line page about batteries, visit the Energizer Learning Center.
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 Different Types of Batteries
 Food – Another Method of Storing Energy

Batteries store energy in a chemical process, but there are other ways of storing energy. Consider the "food chain" on our planet.

Plants, like grass in a meadow, convert the sun's energy through photosynthesis into stored chemical energy. This energy is stored in the plant cells is used by the plant to grow, repair itself and reproduce itself.

Cows and other animals eat the energy stored in the grass or grain and convert that energy into stored energy in their bodies. When we eat meat and other animal products, we in turn, store that energy in our own bodies. We use the stored energy to walk, run, ride a bike or even read a page on the Internet.
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Electrons with a negative charge, can't "jump" through the air to a positively charged atom. They have to wait until there is a link or bridge between the negative area and the positive area. We usually call this bridge a "circuit."

When a bridge is created, the electrons begin moving quickly. Depending on the resistance of the material making up the bridge, they try to get across as fast as they can. If you're not careful, too many electrons can go across at one time and destroy the "bridge" or the circuit, in the process.

In Chapter 3, we learned about electrons and the attraction between positive and negative charges. We also learned that we can create a bridge called a "circuit" between the charges.

We can limit the number of electrons crossing over the "circuit," by letting only a certain number through at a time. And we can make electricity do something for us while they are on their way. For example, we can "make" the electrons "heat" a filament in a bulb, causing it to glow and give off light.
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When we limit the number of electrons that can cross over our circuit, we say we are giving it "resistance". We "resist" letting all the electrons through. This works something like a tollbooth on a freeway bridge. Copper wire is just one type of bridge we use in circuits.

Before electrons can move far, however, they can collide with one of the atoms along the way. This slows them down or even reverses their direction. As a result, they lose energy to the atoms. This energy appears as heat, and the scattering is a resistance to the current.

Think of the bridge as a garden hose. The current of electricity is the water flowing in the hose and the water pressure is the voltage of a circuit. The diameter of the hose is the determining factor for the resistance.

Current refers to the movement of charges. In an electrical circuit – electrons move from the negative pole to the positive. If you connected the positive pole of an electrical source to the negative pole, you create a circuit. This charge changes into electrical energy when the poles are connected in a circuit – similar to connecting the two poles on opposite ends of a battery.

Along the circuit you can have a light bulb and an on-off switch. The light bulb changes the electrical energy into light and heat energy.
 Circuit Experiment