Valence shell
The outer shell of the Atom is referred to as the Valence shell. The number of electrons in the Valence shell determines the electrical characteristics of a material. Electrical Current is defined as electrons in motion. A conductor is a material through which electric current can pass. An insulator is a substance or device that does not readily conduct electricity. A semiconductor is a solid substance. It has a conductivity between that of an insulator and that of a conductor. Materials made from Atoms with less than four valence electrons are termed, Conductors. Those with four are semiconductors. Those with more than four are insulators.
The conductors of our primary interest in their conductivity are as follows:
Silver, Copper, Gold, and Aluminum
Just an example of the many insulators is as follows:
Glass, Mica, Wood, Paper, Ceramic, and Rubber
The semiconductors are as follows:
Germanium, Silicon, and Carbon
Coulombs
What makes Electrons powerful is that the electric charge they possess. It is measured in Coulombs. One Coulomb is equal to the charge of 6.25 times ten to the 18th electrons. An excess or a deficiency of electrons can be measured in terms of coulombs of static charge. If electrons move a magnetic field is produced. In future posts, I will explain how these electrostatic and magnetic fields are controlled. They are used to provide the building blocks for our electrical and electronic systems.
In order to continue a few more terms need to be defined. Voltage(measured in VOLTS) is also referred to as difference of potential or Electromotive Force(EMF). Voltage is the difference in the charge between two points. An example would be the difference in the potential between (across) two battery terminals. So, voltage is measured across two points. Voltage is a stationary thing, it may increase or decrease but it doesn’t move. One of the easiest ways to determine a person’s true understanding of electricity is to catch them interchanging the terms voltage and current.
Current (measured in amperes) is defined as charge in motion or the flow of electrons. Current can be random as in boiling water or directed through a conductor by voltage. Since current is by definition, electrons in motion, it is measured as it passes through a conductor. So, Current is “Through” and Voltage is “Across”. Next is the term Resistance(measured in Ohms) which is the opposition to current.
It should be noted that current can be positive charge flow(+to-) or negative charge flow(-to+). For this entire discussion, I will be using electron flow(negative charge flow) in the explanations.
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