Electronics
Resistor

# The Resistors

In addition the maximum power a resistor can dissipate is indicated. In the experiments you use resistors with a power dissipation of 0.25 watts.

 A selection of resistors of different resistance values. (Enlarge) Circuit symbol resistor.
 The Resistor The resistance of a resistor is provided with the units of Ohm and indicated by the symbol Ω. As symbol in formulas and in circuit diagrams R is used. Commonly used resistors have an electric resistance between a few Ω and a few million Ω... 1 kilo-ohm     = 1 kΩ    = 1,000 Ω 1 mega-ohm    = 1 MΩ   = 1,000,000 Ω

The value of a standard resistance is not printed on the component, but indicated with four colored rings, the color coding. In order to "read" the value you use the table shown...

 Color 1. Ring 2. Ring 3. 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 purple 7 7 10,000,000 gray 8 8 100,000,000 white 9 9 1,000,000,000

Color coding of resistors with 4 rings.

Example...

1. color ring: yelow        = 4
2. color ring: purple     =   7
3. color ring: orange    =      times 1,000
Result:                  = 47,000 Ω = 47 kΩ

The fourth color ring indicates the tolerance. In our example, the fourth color ring is gold, hence the tolerance is 5%. The resistance can therefore have any value between 44,650 Ω and 49,350 Ω.