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Introduction to Resistors Page 1

The most important component to understand in electronics is the resistor. This is because we use the resistor to model much more complex systems. If you understand how to do "resistor math" then solving complex systems becomes much easier.

Lets review the basics.

  • They come in various values that are expressed in Ohms.
  • You can determine their value by using either a multimeter or by reading the colored bands on them.
  • A resistor is used to resist current flow.

We need to introduce a new symbol because it is used extensively in electronics.

The symbol for an ohm is Ω.

Whenever you see Ω written down, you can say "ohm" or "ohms" if plural.

Here is the schematic symbol for a resistor, and some real life examples.

Schematic Symbol
Actual Image

Expected Values of Resistors

Resistors come in many different values from 1 Ohm to 10 million Ohms. Since it is very inconvenient to write 10,000,000 out, it is common to express the values of resistors in Engineering Notation. While engineering notation is a broad concept, you really only need to know 2 terms when dealing with resistors.

Name Multiply By
Kilo 1,000
Mega 1,000,000

Kilo and Mega are the greek prefixs that mean 1,000 and 1,000,000 respectively. So if I told you that a resistor was 5k, then you know that I really mean this.

5k = 5 x 1000 = 5,000 ohms or 5,000Ω (pronounced 5 kilohms)

Likewise, 5M is the same as this.

5M = 5 x 1,000,000 = 5,000,000 ohms or 5,000,000Ω (pronounce 5 megaohms)

Some common resistor values are listed in the table below. You should be familiar with these values because you will see them a lot in electronics.

Name Value
100 100Ω
1k 1,000Ω
2.2k 2,200Ω
4.7k 4,700Ω
100k 100,000Ω
1M 1,000,000Ω
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Jason Bauer

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Jason Bauer is an owner and programmer for He's allergic to twitter and facebook, but you can find more of his articles in the Guides section.
Friday, 25-May-2018 17:28:52 PDT