Chapter 4

Ohm

Represented as the greek symbol omega.

Mho

Represented by an upside down omega.

Resistance ®

Resistance that opposes the flow of current in a circuit.

Series circuit

A type of circuit designed to have a single path flow through for current. This path results in adding up all voltage sources while current stays the same.

Parallel circuit

A type of circuit having branching paths and have their voltage sources set across from each other. This results in increasing current and voltage staying the same.

Wirewound resistor

A type of resistor constructed of a nickel-chromium alloy, which is a mixture of metals. Leads are attached and the entire resistor is sealed with a coating. Wirewound resistors are used in high current circuits where precision is necessary. The resistance range can vary from a fraction of an ohm to several thousand ohms. Can be adjusted to the length on how you need it to operate.

Carbon composition resistor

A type of resistor that was used in electronic circuits/ It is a compacted material that has a great deal more resistive properties than conductive properties.

Rheostat

A variable resistor used to control current.

Film resistor

A very thin film of material to create a type of resistor. They have become popular because they offer the small size of the composition resistor with the accuracy of the wirewound resistor.

Variable resistor

Allows the resistance to vary depending on the application the resistor can be used for such as a radio for example.

The color code chart

Black 0, Brown 1, Red 2, Orange 3, Yellow 4, green 5, blue 6, violet 7, Grey 8, and white 9. Gold, when used as a multiplier, is 0.1 and silver is 0.01. Gold and silver for tolerance are 5% with silver being 10%.

Resistor

Components manufactured to possess a specific value of resistance to the flow of current.A resistor is the most commonly used component in an electronic circuit and helps to resist the flow of current in a circuit.

Potentiometer

Is a variable resistor used to control voltage.

Color code

It is the resistance value listed on a very small resistor, usually found on carbon or film based resistors. The first color band is the first digit, the second band is the second digit, and the third band is the multiplier or the number of zeros on that resistor. The fourth colored band is the amount of tolerance that resistor can tolerate. A reliability band, depending on the resistor, does not count as a band on the resistor. If there is no tolerance band, then it will be a plus or minus twenty-percent.

Surface mount resistor

Surface mounts are going to be smaller and miniaturized and are ideal for smaller circuit applications. A thin film of carbon or metal alloy is deposited on a ceramic base or substrate.

Tolerance

The amount of tolerance is the amount that a resistor can tolerate. So, for instance, the tolerance in a resistance pertains to how much of a percentage that a particular resistance can tolerate. So a resistor, for example, can tolerate 20% or below 20% for example. This is all depended on the color coding on the resistor.

Branch

The different paths on a parallel circuit.

Siemen

The unit of conductance which is the opposite of resistance.

Conductance (G)

This is the ability for a material to pass electrons. The best known conductors are from greatest to lowest: Silver, copper, lead, gold aluminum, iron, and platinum.

Resistor color code

Value from resistor color code 1-9

Series

parallel circuit- A type of combo circuit where single path series circuits are set in a parallel formation to increase both voltage and current in a circuit.