In a previous post we had a look at transistors, in the next few posts we will look at 3 other basic electronic components; resistors, capacitors and diodes.

Let us start with the most basic of the 3 today, the resistor. As their name suggest, they resist the flow of electrical current through a circuit. The change in current can be determined using Ohm’s Law, which states that the current flowing through a conductor equals the Voltage across the conductor divided by the resistance present in the conductor, or  I = V/R, where I represents current (measured in Amps), V represents Voltage (measured in Volts) and R represents the resistance (measured in Ohms Ω).

Resistors have coloured stripes along their sides which are used to indicate their values, here is the table used for value lookup:

Colour Value
Black 0
Brown 1
Red 2
Orange 3
Yellow 4
Green 5
Blue 6
Violet 7
Grey 8
White 9

A simple way to remember the sequence of the colours is with the rhyme:
Better Be Right Or Your Great Big Venture Goes Wrong.

The last stripe indicates the tolerance of the resistor:

Colour Value
Brown ±1%
Red ±2%
Gold ±5%
Silver ±10%

Here is an example of how to utilise the table:

resistor 220

The resistor above has 3 colour stripes and a tolerance stripe.

Red Red Brown with a Gold tolerance stripe.

This translates to:

2 2 x 10¹ ± 5% = 220Ω ±5%

Now for an example with a Resistor with 5 stripes:

resistor 10k

The resistor above has 4 colour stripes and a tolerance stripe.

Brown Black Black Red and a Gold tolerance stripe.

This Translates to:

1 0 0 x 10²± 5% = 10,000Ω ±5% = 10kΩ ±5%

Here is the schematic used to represent Resistors in a circuit diagram:

Resistor Symbol


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