Question #211162

Compute the total resistance of you to following the procedure in the resistance measurement using the ohmmeter and color coding chart compare the reading very (measured value)with the color-coded value

Expert's answer

Tolerance exists in resistors. That is, they cannot all be produced to the same level of resistance.

The fourth band shows the tolerance of a resistor. Again, silver represents 10% of the total, gold represents 5%, and red represents 2%.

A 10 kilohm resistor with a 10% tolerance might read as low as 9k and as high as 11k and yet be considered ‘within' tolerance.

The greater the value, the greater the potential gap between marked and real worth.

Tolerance is also linked to why resistors have standard values.

10% resistors follow the E12 series. Because the value might fluctuate by +/- 10%, just a certain number of resistors are required to cover a full decade of values.

Begin with 10 ohms, for example. This might be as low as 9 ohms or as high as 11 ohms. The series continues with 12 ohms. That may be 10% less (10.8 ohms) or 10% more (10.8 ohms) (13.2 ohms). As you can see, the ranges covered by the 10 ohm and 12-ohm resistors really overlap.

The rest of the E12 series continues as follows:

12 values, plus or minus 10%, span the whole range from 10 to 90 odd ohms. The same is true if you go up a decade. So your 100-ohm resistor might have a resistance as low as 90 ohms (overlapping slightly with the 82-ohm resistor).

Obviously, you may go with 5% resistors and the E24 series if you want a bit more granularity and precision. But, again, the tolerance allows for a little amount of overlap between nominal values.

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