Energy is one of the most fundamental parts of our universeWe use energy to do work. Energy lights our cities. Energy powers our vehicles, trains, planes and rockets. Energy warms our homes, cooks our food, plays our music, gives us pictures on television. Energy powers machinery in factories and tractors on a farm.
Energy from the sun gives us light during the day. It dries our clothes when they're hanging outside on a clothes line. It helps plants grow. Energy stored in plants is eaten by animals, giving them energy. And predator animals eat their prey, which gives the predator animal energy.
Everything we do is connected to energy in one form or another.
Energy is defined as: "the ability to do work."
There are many sources of energy. In The Energy Story, we will look at the energy that makes our world work. Energy is an important part of our daily lives.
The forms of energy we will look at include:
- Electricity
- Biomass Energy - energy from plants
- Geothermal Energy
- Fossil Fuels - Coal, Oil and Natural Gas
- Hydro Power and Ocean Energy
- Nuclear Energy
- Solar Energy
- Wind Energy
- Transportation Energy
Energy - What Is It?
Energy causes things to happen around us. Look out the window.
During the day, the sun gives out light and heat energy. At night, street lamps use electrical energy to light our way.
When a car drives by, it is being powered by gasoline, a type of stored energy.
The food we eat contains energy. We use that energy to work and play.
We learned the definition of energy in the introduction:
"Energy Is the Ability to Do Work."
Energy can be found in a number of different forms. It can be chemical energy, electrical energy, heat (thermal energy), light (radiant energy), mechanical energy, and nuclear energy.
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.
Another type of electrical energy is static electricity. Unlike current electricity that moves, static electricity stays in one place.
Try this experiment...
Rub a balloon filled with air on a wool sweater or on your hair. Then hold it up to a wall. The balloon will stay there by itself.
Tie strings to the ends of two balloons. Now rub the two balloons together, hold them by strings at the end and put them next to each other. They'll move apart.
Rubbing the balloons gives them static electricity. When you rub the balloon it picks up extra electrons from the sweater or your hair and becomes slightly negatively charged.
The negative charges in the single balloon are attracted to the positive charges in the wall.
The two balloons hanging by strings both have negative charges. Negative charges always repel negative charges and positive always repels positive charges. So, the two balloons' negative charges "push" each other apart.
Static electricity can also give you a shock. If you walk across a carpet, shuffling your feet and touching something made of metal, a spark can jump between you and the metal object. Shuffling your feet picks up additional electrons spread over your body. When you touch a metal doorknob or something with a positive charge the electricity jumps across the small gap from your fingers just before you touch the metal knob. If you walk across a carpet and touch a computer case, you can damage the computer.
One other type of static electricity is very spectacular. It's the lightning in a thunder and lightning storm. Clouds become negatively charged as ice crystals inside the clouds rub up against each other. Meanwhile, on the ground, the positive charge increases. The clouds get so highly charged that the electrons jump from the ground to the cloud, or from one cloud to another cloud. This causes a huge spark of static electricity in the sky that we call lightning.
You can find out more about lightning at Web Weather for Kids -www.ucar.edu/40th/webweather/
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