The Resistor

Resistors or fixed value resistors are available in a variety of designs and resistance values. Unless otherwise indicated, resistors with a power rating of 0.25 watts are used in the experiments.

A selection of resistors of different resistance values. (Enlarge)

Circuit symbol resistor.

Resistance

The electric resistance of a resistor is specified with the unit ohm and abbreviated with the symbol Ω. In formulas and in circuit diagrams the resistor is abbreviated by R.

Frequently used resistors have an electrical resistance of only a few Ω to several million Ω...

1 Kilo-Ohm = 1 kΩ = 1,000 Ω

1 Mega-Ohm = 1 MΩ = 1,000,000 Ω

The value of a standard resistor of the E12 series (see table) is specified by four colored rings, the color coding. To "read" the value, you use the table ...

Color	1^st Ring	2^nd Ring	3^rd Ring
black	—	0	1
brown	1	1	10
red	2	2	100
orange	3	3	1,000
yellow	4	4	10,000
green	5	5	100,000
blue	6	6	1,000,000
violet	7	7	10,000,000
gray	8	8	100,000,000
white	9	9	1,000,000,000