INSTALLER TECHNICIAN Exploring Electrons and andElectricity Module #
LESSON OBJECTIVES LESSON OBJECTIVES Summarize major characteristics of electron orbits and orbital shells. (pg’s 2-3) Summarize major characteristics of electron orbits and orbital shells. (pg’s 2-3) Define electron characteristics of the shell capacity, valence shell, and electron energy level. (pg’s 3-6) Define electron characteristics of the shell capacity, valence shell, and electron energy level. (pg’s 3-6) Define and identify the types of conductors and insulators. (pg’s 7-8) Define and identify the types of conductors and insulators. (pg’s 7-8) Define semiconductor characteristics. (pg 9) Define semiconductor characteristics. (pg 9) Describe electron current flow. (pg’s 10-11) Describe electron current flow. (pg’s 10-11)
LESSON OBJECTIVES LESSON OBJECTIVES Describe energy transfer that produces electrical current. (pg 12) Describe energy transfer that produces electrical current. (pg 12) Define the electrical current characteristics regarding speed and the amount of current. (pg’s 12-13) Define the electrical current characteristics regarding speed and the amount of current. (pg’s 12-13) Define electromotive force, potential difference, and voltage (pg’s 16-17) Define electromotive force, potential difference, and voltage (pg’s 16-17) List the units of measurement for voltage (pg 20) List the units of measurement for voltage (pg 20) List the units of measurement for current (pg 20) List the units of measurement for current (pg 20)
Conductors, Semiconductors & Insulators Most materials belong to one of three broad groups: conductors, insulators, and semiconductors. The borderlines are not clear, though, and many substances cannot easily be put into one group or the other.
Atomic structure of conductors, insulators, and semiconductors Insulator - full valence shell Conductor - 1 to 2 valence electrons Semiconductor - 4 valence electrons
Atomic structure of conductors, insulators, and semiconductors Conductor - 1 to 2 valence electrons IMPORTANT The 3rd orbital shell has a maximum capacity of 18 electrons
Atomic structure of conductors, insulators, and semiconductors Insulator - full valence shell
Atomic structure of conductors, insulators, and semiconductors Semiconductor - 4 valence electrons IMPORTANT NOTE: The # of valence electrons in the valence shell determines what a particular element it is.
Structure of an atom Neutron Proton Electron Shell or energy level
Electricity-the flow of free electrons Bound electron Free electron Valance electron Negative source Positive source
N N N N The center of an atom is called the nucleus. Most atoms have neutrons which have no charge. A nucleus also has protons and they have a positive charge. Negative electrons orbit the nucleus.
N N N N Negative electrons orbit the nucleus. IMPORTANT NOTE: The attraction between the positive nucleus and the negative electrons keep the electrons from breaking away from the nucleus even at high speeds.
N N N N This is a copper atom. It has 29 protons. It has 29 electrons. Its net charge = 0. Valence electron
N N N N Its attraction to the nucleus is relatively weak.
The valence electron The nucleus plus the inner electron orbits A simple model of the copper atom looks like this:
Copper wire is used to conduct electricity because the valence electrons move freely through its structure. Remember, the valence electrons are weakly attracted to the nuclei.
So far, we know that copper’s single valence electron makes it a good conductor. It acts as an electrical insulator. The rule of eight states that a material like this would be stable since its valence orbit is full. No Vacancy
VOLTAGE & CURRENT VOLTAGE = VOLTS VOLTAGE = VOLTS AC = AC = DC = DC = CURRENT = AMPERES (A) CURRENT = AMPERES (A)
VOLTAGE - The difference in electric potential between two charges. 1 Volt - Difference in Electric Charge 1 Ohm of Resistance Produces 1 Ampere of Current Flow. * IMPORTANT *
CURRENT - The rate of flow of electrons Measurement Point = One Coulomb Per Second = One Ampere
piconanomicromilli0KiloMegaGigaTerra Metric Prefixes USING UNITS OF ELECTRICAL MEASUREMENTS ______1______ 1____ ,000,000,000 1,000,000,000,000 1,000,000 1,000,000 _______1______ ___1___ 1,000,000,000,000 1,000,000, (p) (n) (u) (m) (K) (M) (G) (T)
m (MILLI) PREFIX CHART BASE UNITS Movement of Decimal Point to and from Base Units 3 3 M (MEGA ) k (KILO) 3 3 (MICRO)
EXAMPLES OF CONVERTING UNITS A =___ mA 12 (move 3 decimal places to the right) 450 mA = ___ A (move 3 decimal places to the left) = ___ kk (move 3 decimal places to the left) M = _________ (move 6 decimal places to the right) A = _________A (move 6 decimal places to the left)