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I was asked to find the four colour stripes of a 1M ohm (tolerance of 5%)

My question now is don't we have 2 options? I came up with:

  • Black(0) Brown(1) Blue(x1M) Gold (5%)

  • Brown(1) Black(0) Green(x100K) Gold(5%)

Is there one right and one wrong or are both of these correct?

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2 Answers 2

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You are not allowed to start with black except for zero ohm jumper, so only your second suggestion is valid.

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    \$\begingroup\$ I always breathe a sigh of relief with answers like this when someone new to EE asks a simple question that's surprisingly sharp, and the answer is "Don't worry, the people who made the standards thought of that one!" \$\endgroup\$
    – Cort Ammon
    Commented Apr 2, 2017 at 17:45
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What if you wanted the colours of a 1.5 Mohm resistor? Your first option doesn't give any ability to specify a 2nd digit so clearly it is a bad choice. The second option allows colours of brown, green and green meaning 15 x 100 kohm.

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  • \$\begingroup\$ Out of interest what exactly would make this a problem? My initial thought is that how you represent a 1Mohm resistor should have no bearing on how you represent a 1.5Mohm resistor. That is why could you not have brown green green for the latter while still having either of the OPs choices for the 1Mohm. \$\endgroup\$
    – Chris
    Commented Apr 3, 2017 at 10:52
  • \$\begingroup\$ @Chris - I have my own first thought and it differs with your first thought. Consistency and simplicity is my main concern. \$\endgroup\$
    – Andy aka
    Commented Apr 3, 2017 at 14:11
  • \$\begingroup\$ And I guess that is why the rule in winny's answer. I guess you explained reasoning for the rule rather than stating it was actually a rule but it comes across as more of an opinion than a rule - ie that you are saying you should do it that way rather than it being the only actually correct way. \$\endgroup\$
    – Chris
    Commented Apr 3, 2017 at 15:15

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