Ohm’s Law
In 1827, George Simon Ohm discovered that there was a definite relationship between voltage, current, and resistance in an electrical circuit. Ohm’s Law defines this relationship and can be stated in three ways.
1. Applied voltage equals circuit current times the circuit resistance. Equation (1-2) is a mathematical respresentation of this concept.
2. Current is [...]
System Internationale (SI) Metric System
Electrical units of measurement are based on the International (metric) System, also known as the SI System. Units of electrical measurement include the following:
Ampere
Volt
Ohm
Siemens
Watt
Henry
Farad
Appendix A provides more information concerning the metric system, metric prefixes, and powers of 10 that are used in electrical measuring units.
Voltage
Voltage, electromotive force (emf), or potential difference, [...]
Conductors
Conductors are materials with electrons that are loosely bound to their atoms, or materials that permit free motion of a large number of electrons. Atoms with only one valence electron, such as copper, silver, and gold, are examples of good conductors. Most metals are good conductors.
Insulators
Insulators, or nonconductors, are materials with electrons that are tightly [...]
Potential Difference
Potential difference is the term used to describe how large the electrostatic force is between two charged objects. If a charged body is placed between two objects with a potential difference, the charged body will try to move in one direction, depending upon the polarity of the object. If an electron is placed between [...]
Electrostatic Field
A special force is acting between the charged objects discussed above. Forces of this type are the result of an electrostatic field that exists around each charged particle or object. This electrostatic field, and the force it creates, can be illustrated with lines called “lines of force” as shown in Figure 4.
Charged objects repel [...]
Electrostatic Forces
One of the mysteries of the atom is that the electron and the nucleus attract each other. This attraction is called electrostatic force, the force that holds the electron in orbit. This force may be illustrated with lines as shown in Figure 3.
Without this electrostatic force, the electron, which is traveling at high speed, [...]
The Atom
Elements are the basic building blocks of all matter. The atom is the smallest particle to which an element can be reduced while still keeping the properties of that element. An atom consists of a positively charged nucleus surrounded by negatively charged electrons, so that the atom as a whole is electrically neutral. The [...]