A Test

[rsdoran]

I'd be pretty hesitant to use these tests.
Even their sample questions have some pretty blaring errors.
See the resistor color code question on that page to see what I mean.

I am not sure what you mean exactly. I assume that you are referring to the lack of bands. This was meant as a simple test..if I saw it I would think Red 2 Brown 1 and since Gold is a multiplier at .1 then its a 2.1ohm resistor. Without a 4th band then resistance would be 20%.

 

[LadderLogic]

I have to admit I would've failed that one.
I don't remember the resistor color code by heart... for the half of my career I was dealing with the resistors that had the values printed on'em.
On the other hand, if there is something a controls guy must have memorized, it is the multiplication table... I don't think anybody ever gives any tests for that.

 

[rsdoran]

I failed it too with how I wrote the answer.

I would think Red 2 Brown 1 and since Gold is a multiplier at .1 then its a 2.1ohm resistor. Without a 4th band then resistance would be 20%.

Tolerance would be 20%

On 4 band resistors the first 2 bands represent a number..ie in this case 21 the third band is a multiplier...gold is .1 and the fourth band is TOLERANCE where gold silver etc are normally used, when there is no fourth band the tolerance is understood to be as high as 20%.

They also make 5 and 6 band resistors that follow a slightly different method.

 

[jimbo3123]

My mistake.
I never knew that gold was used as a multiplier as well as a tolerance.

I guess I learn something new every day.