Organic Rankine Cycle
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What Is Electricity?
What Is Electricity?
Electricity is the flow of electrons that occurs when a charged (unbalanced) molecular state moves toward a more stable (balanced) state...whatever that means.
Most of us use electricity every day without really knowing what it is or how it works. Though we may know that we don’t have to cap our wall outlets to prevent electricity from spilling onto our carpet, many of us just use our electricity without asking any questions. When living with a renewable energy system, even one installed by a paid professional, the importance of understanding our electrical supply and demand becomes more important. We need to be able to read the meters that tell us how much power we’re making and how much we’re using. We need to conceive our system’s ability to handle a given instantaneous load as well as loads over time. We need to be able to evaluate potential loads to determine their practicality. All in all, renewable energy systems require a greater level of user involvement than do “plug in—pay the bill” utility grid systems. This involvement can be extremely gratifying, even fun, as we monitor the power that we create and use. The satisfaction of limiting our energy usage and obtaining our power from clean renewable sources is intensified by our understanding of, and interaction with, the process. This involvement requires only a basic understanding of electricity and its properties.
Kinds of Electricity
Electricity is usually classified as one of three types, static, direct current (DC), or alternating current (ac). As we try to understand electricity we will move through descriptions of all three types. Starting with static electricity will help us understand direct current, which will in turn help us understand alternating current. This article is about the fundamentals of direct current electricity. With this knowledge we should be ready for the discussion of alternating current on page 73 in this issue.
Static Electricity and State of Charge
Most of us are familiar with certain forms of static electricity. Shuffling across the carpet in socks creates static electricity. We can see the effect when we touch a pussy cat’s nose. Rubbing a balloon on your little brother’s head creates static electricity too. We can see the effect when his hair stands on end and when the balloon sticks to the wall. In both these cases we have
used friction to create a static electric charge. Another example of friction causing static electricity is lightning. The friction between clouds or between the clouds and the earth creates a powerful static charge. We see and hear the effect in the flash of lightning and the clap of thunder.
The static charge in all of these situations is based on the creation of an electrical imbalance between two objects. To understand this imbalance we must look at an atomic level. Look at the diagram of the hydrogen atom in side bar 2. This simplest of all atoms shows two of three possible components that make up any atom. In the center (nucleus) is a proton. A proton carries a positive (+) charge. The outer component is called an electron. It carries a negative (-) charge. The amount of negative charge that an electron carries is the same for any electron in any atom. The same is true for the positive charge of any proton. In the hydrogen atom shown here, the charge of the electron cancels or balances the charge of the proton creating an electrically neutral atom. The number of protons and electrons in the atoms of different elements vary. For example, the copper atom has 29 protons and 29 electrons. The number of protons and electrons in any element are normally equal. In this balanced state, the positive charge of the protons equals the negative charge of the electrons and the atom is electrically balanced.
The third component of an atom is the neutron, which resides in the nucleus with the proton. As its name suggests the neutron has no charge associated with it. Therefore, while it’s important in defining the atom, it plays no role in electrical balance.
A charge is created when a substance loses the balance between the number of electrons and protons in its atoms. In the examples of static electricity, it was friction that stripped the electrons from one substance and left them as excess with another. A static charge can also be created through chemical reaction, as in a battery. The substance with missing electrons has a positive charge while the substance with extra electrons has a negative charge (remember that electrons have a negative charge).
64 Home Power #52 • April / May 1996
R= E2 P
1C = 6.28 x 1018e
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