2007-08-28 15:57:21 · 6 answers · asked by Eric D 1 in Science & Mathematics ➔ Engineering
Resistors are sold with a certain tolerance and are not guaranteed to be closer to a specific value than that percentage of precision.
In reality nowadays they make a load of them that are aimed at a specific value and then sort them automatically. If they try to make one that is 27000 Ohms they then run it through an automated Ohmmeter. If it is 20% higher or lower they put on a marking that says it is 27000 Ohms +-20%. If it happened to be within 1% of 27000 Ohms they put on a marking that says it is 27000 Ohms +- 1%. The more-accurate ones are sold for a higher price than the less accurate ones. In reality it was just random chance that made one closer to the target than another but it is a great way to raise your income from selling a commodity.
2007-08-28 16:16:26 · answer #1 · answered by Rich Z 7 · 1⤊ 0⤋
Values Of Resistors
2016-12-12 15:44:34 · answer #2 · answered by ? 4 · 0⤊ 0⤋
the actual value of a resistor is not specified as an absolute value but there is a nominal value and a tolerance value.
A resistor can have tolerances of 20%, 10%, 5%, 1% and even of 0.5% or better.
So a resistor of a nominal value of 1000 ohms and a tolerance of 5% can have any value from 950 ohms to 1050 ohms.
Of course, the smaller tolerance the more expensive resistor
2007-08-28 16:44:10 · answer #3 · answered by Anonymous · 3⤊ 0⤋
Rich Z has it right and the story gets a little worse. If you get a bunch of cheap resistors, say 20% units, and think you can sort them out by hand and get some 1% units without paying their premium price, well you are out of luck. The 1% units were already culled out at the factory, so in fact the ones you have marked 20% are almost absolutely farther out than 1% or 5% or 10%. No free lunch.
2007-08-28 21:02:02 · answer #4 · answered by ZORCH 6 · 0⤊ 0⤋
It may be due to the temperature. The data sheet of the resistor would provide the resistance(stated resistance) for the room temperature.If there is any difference in temperature, it would have an effect. If the temperature is greater, the resistance also increases.
2007-08-28 19:20:51 · answer #5 · answered by yegs 1 · 0⤊ 0⤋
I asked this very same question in lab earlier today. I'm told that despite my past experience, they shouldn't be.
2007-08-28 16:05:30 · answer #6 · answered by Avatar of Hypnos 2 · 0⤊ 0⤋