We are now learning about the different forms of energy and how they can be changed and used for our benefit. Here's an overview:

There are 8 basic forms of energy. 5 of these are "active" energies that involve movement (they are categorized as "kinetic energy"). 3 of these are "stored" energies that are not doing anything (they are categorized as "potential energy").

Forms of Energy

Kinetic (active)

Light

* also called radiant energy

* travels in waves

* the only energy we can see

Example: light from a light bulb

Sound

* travels by compression waves through a substance

* the only energy we can hear

Example: the music from a radio

Heat

* the internal energy of an object's atoms moving in place

Example: heat from a hot pan

Electric

* the energy of electrons "flowing" within a substance

Example: electricity moving through wires in the wall

Motion

* also called simply "kinetic energy"

* the energy of moving objects

Example: a ball flying through the air

Potential (stored)

Gravitational

* the energy an object has due to position or height

Example: a boulder at the top of a cliff, ready to fall

Chemical

* energy stored in chemical bonds

Example: the energy used in photosynthesis to hold together the carbon, hydrogen, and oxygen in sugars

Nuclear

* the energy holding the nucleus of an atom together

Example: the energy released by a nuclear bomb

Law of Conservation of Energy:

Energy can not be destroyed or created. Its form can be changed.

This basically says that we can never destroy energy or create it. We can, however, change the energy's form any number of times.

Here's an example:

Light energy leaves the sun and travels to the earth. It hits a plant leaf, where it is changed (transformed) into chemical energy during photosynthesis (to make the sugar). We eat the plant to get that stored chemical energy. Out bodies hold the energy until we need to move, when we change that stored chemical energy into motion energy as we run or walk.

Another example:

Millions of years ago, light energy leaves the sun and travels to the earth. It hits a plant leaf, where it is changed (transformed) into chemical energy during photosynthesis (to make the sugar). At some point, the plant falls over and is covered by tons of mud and rock. The pressure and heat cause the plant to turn into coal (still, stored chemical energy). Humans dig up the coal and burn it at a power plant, changing that energy into heat energy. This heat is used to boil water, changing the heat into motion energy of expanding steam. The steam turns a turbine generator, which transforms the motion energy into electric energy. That energy is then sent to a house and through a lamp, where it is transformed back into light energy.

Any time something is burned, it is changing stored chemical energy into heat energy (and possible some light energy).

Generators:

A generator is a set of magnets on a rotating shaft inside a coil of copper wire. The magnets produce an invisible force field (the magnetic field) that extends through the copper wire.

As the magnets spin, the invisible magnetic fields from the magnets push the electrons in the wire coil through the wire. This is kind of like the paddles of a waterwheel pushing water in front of them. This transforms the motion energy of the spinning magnets into electric energy.