TH 1501 Stage Lighting I
Electrical Theory

Parts of the Atom

Conductors

• Substances which have electrons that move easily from one atom to the next are considered conductors.
• Insulators are materials that resist the release of their electrons.
• Electricity always follows the path of least resistance.
• Given enough pressure (electromotive force or EMF), electricity must go somewhere.
  

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Electrical Conductors


Copper

 

Other Electrical Conductors
Silver, Brass, Aluminum

Insulators
Glass, Rubber, Fiber

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Electrical Terminology

Volts Currents and Basic Electricity Concepts

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Electrical Systems

• Voltage: Source of electrical potential - electromotive force.
• Current: Unbroken path (circuit) that channels flow of electrons.
• Resistance: Work or load needed to control current flow.

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Ohm's Law: I = E/R

• As electromotive force increases, current increases.
• As resistance increases, current decreases.

I = quantity of electrons moving through circuit measured in amperes.
E = electrical pressure in the circuit measured in voltage.
R = resistance in the circuit measured in ohms.
P = amount of work circuit is capable of providing measured in watts.

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West Virginia Law
W = V x A

A = current measured in amperes.
V = electromotive force measured in voltage.
W = energy available measured in wattage.

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Types of Circuits

Electrical Circuits Explained

Series
Increasing amounts of resistance to same circuit, current decreases.

Parallel
Increasing amounts of pressure to same circuit, current increases.

Combination Circuits
Some components in series, others in parallel.

Types of Electromotive Force

Direct Current (DC)
Battery University

Carbon Zinc Batteries General Purpose Clocks Flashlights Calculators Portable Electronics	Lithium Batteries Light weight High energy Portable computers Cell phones Watches
Alkaline Batteries Excellent storage life Portable audio systems Cameras Toys High power flashlights Pagers	Nickel Cadmium (Ni-Cad) Battery Rechargeable Recyclable Built-in charge level indicator
Lead Acid Battery Wet cell and dry cell Cars and trucks	Photovolactic

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How Alternating Current (AC) Works

Electrical Turbine

Construction of a Sine Wave

Turbine Cross Section Demonstrating Rotating Magnetic Fields

United States Alternating Current Standard
Three Phase 60 Cycles per Second

Three Phase Sine Wave

Electrical Safety

Why a ground wire?

Why electrical breakers?

Types of Wire Conductors
Solid
Stranded wire

American Wire Gauges
16 Gauge Wire: 6 amps x 120 volts = 720 watts
14 Gauge Wire: 15 amps x 120 volts = 1,680 watts
12 Gauge Wire: 20 amps x 120 volts = 2,400 watts