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
Energizer Bunny
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.
Sidebar
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
We learned in Chapter 8 that fossil fuels were formed before and during the time of the dinosaurs – when plants and animals died. Their decomposed remains gradually changed over the years to form coal, oil and natural gas. Fossil fuels took millions of years to make. We are using up the fuels formed more than 65 million years ago. They can't be renewed; they can't be made again. We can save fossil fuels by conserving and finding ways to harness energy from seemingly "endless sources," like the sun and the wind.
We can't use fossil fuels forever as they are a non-renewable and finite resource. Some people suggest that we should start using hydrogen.
Hydrogen is a colorless, odorless gas that accounts for 75 percent of the entire universe's mass. Hydrogen is found on Earth only in combination with other elements such as oxygen, carbon and nitrogen. To use hydrogen, it must be separated from these other elements.
Today, hydrogen is used primarily in ammonia manufacturing, petroleum refining and synthesis of methanol. It's also used in NASA's space program as fuel for the space shuttles, and in fuel cells that provide heat, electricity and drinking water for astronauts. Fuel cells are devices that directly convert hydrogen into electricity. In the future, hydrogen could be used to fuel vehicles (such as the DaimlerChrysler NeCar 4 shown in the picture to the right) and aircraft, and provide power for our homes and offices.
Hydrogen can be made from molecules called hydrocarbons by applying heat, a process known as "reforming" hydrogen. This process makes hydrogen from natural gas. An electrical current can also be used to separate water into its components of oxygen and hydrogen in a process called electrolysis. Some algae and bacteria, using sunlight as their energy source, give off hydrogen under certain conditions.
Hydrogen as a fuel is high in energy, yet a machine that burns pure hydrogen produces almost zero pollution. NASA has used liquid hydrogen since the 1970s to propel rockets and now the space shuttle into orbit. Hydrogen fuel cells power the shuttle's electrical systems, producing a clean by-product – pure water, which the crew drinks.
You can think of a fuel cell as a battery that is constantly replenished by adding fuel to it – it never loses its charge.
Fuel Cell Uses
Solar Power Satellites
Other Ideas
Some of the energy we can use is called renewable energy. These
include solar, wind, geothermal and hydro. These types of energy are
constantly being renewed or restored.
In your home, you can save energy by turning off appliances, TVs and radios that are not being used, watched or listened to.
In California, about one-half of ALL the energy we use
goes into transportation – cars, planes, trucks, motorcycles, trains,
buses. And of all the oil we use in the state about three-quarters of
all it goes into making gasoline and diesel fuel for vehicles.
Fourteen billion gallons of gasoline is enough to fill a
line of 10,000 gallon tanker trucks stretched bumper to bumper from San
Francisco to San Diego, back to San Francisco, and then part of the way
to Sacramento!
Because of concerns about air pollution and
petroleum-dependence, new clean-burning fuels made from fuels other than
oil are being introduced. These fuels include methanol, ethanol,
natural gas, propane and even electricity. The car on the right uses
methanol, the same fuel used in Indianapolis Speedway race cars.
Wind can be used to do work. The kinetic energy of the wind can
be changed into other forms of energy, either mechanical energy or
electrical energy.
Blowing wind spins the blades on a wind turbine – just like a
large toy pinwheel. This device is called a wind turbine and not a
windmill. A windmill grinds or mills grain, or is used to pump water.
You can use a single smaller wind turbine to power a home or a
school. A small turbine makes enough energy for a house. In the picture
on the left, the children at this Iowa school are playing beneath a wind
turbine that makes enough electricity to power their entire school.
Together these three places in California make enough
electricity to supply an entire city the size of San Francisco! About
11 percent of the entire world's wind-generated electricity is found in
California. Other countries that use a lot of wind energy are Denmark
and Germany.
We have always used the energy of the sun as far back as humans
have existed on this planet. As far back as 5,000 years ago, people
"worshipped" the sun. Ra, the sun-god, who was considered the first king
of Egypt. In Mesopotamia, the sun-god Shamash was a major deity and was
equated with justice. In Greece there were two sun deities, Apollo and
Helios. The influence of the sun also appears in other religions –
Zoroastrianism, Mithraism, Roman religion, Hinduism, Buddhism, the
Druids of England, the Aztecs of Mexico, the Incas of Peru, and many
Native American tribes.
The world's ocean may eventually provide us with energy to
power our homes and businesses. Right now, there are very few ocean
energy power plants and most are fairly small. But how can we get energy
from the ocean?
Wave Energy
Geothermal Energy has been around for as long as the Earth has
existed. "Geo" means earth, and "thermal" means heat. So, geothermal
means earth-heat.
For every 100 meters you go below ground, the
temperature of the rock increases about 3 degrees Celsius. Or for every
328 feet below ground, the temperature increases 5.4 degrees Fahrenheit.
So, if you went about 10,000 feet below ground, the temperature of the
rock would be hot enough to boil water.
When this hot water comes up through a crack in the earth, we
call it a hot spring, like Emerald Pool at Yellowstone National Park
pictured on the left. Or, it sometimes explodes into the air as a
geyser, like Old Faithful Geyser pictured on the right.