Electrical Lessons

Basic Electronics
Chapter 2
Basic Electrical Principles and the Functions of Components
Figures in this course book are reproduced with the permission of the American Radio Relay League.
This booklet was compiled by
John P. Cross AB5OX

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Basic Electrical Principles
• Conductors - keep loose grip on their electrons and allow electrons to move freely. Metals are usually good conductors. • Insulators - keep close hold of their electrons and do not allow free movement of electrons. Glass, wood, plastic, mica, fiberglass and air are good insulators.
• Electromotive Force (EMF) is the force that moves electrons through conductors. Its unit of measure is the
Volt. Think of it as pressure.
• Voltage Source - has two terminals (+ and -). Some examples are car batteries (12 volts DC), D cell batteries
(1.5 volts DC) and a wall socket (120 volts AC).
• Current - is the flow of electrons. It is measured in amperes. • Resistance (ohms, Ω) is the ability to oppose an electrical current. PHYS 401 Physics of Ham Radio

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PHYS 401 Physics of Ham Radio

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Circuit Definitions

A circuit must close to be complete!

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Ohm’s Law
• Ohm’s Law relates Current (I), Voltage (E) and Resistance
(R)
• The relationship can be written three ways:
»E=IxR
»I=E/R
» R = E/I

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Resistors

Mnemonic: “Black Bears Run On Young
Grass By Violets Growing Wild”
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Resistor Types - Precision

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Resistors - Film Type

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Resistors - Variable

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Calculating Resistance

• Parallel:

• Series:
R=R1+R2+R3+R4
(the voltage adds up)

1/R=1/R1+1/R2+1/R3
(the current adds up)

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Capacitors
• Capacitors store