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Difficulty: EasyResistors and Potentiometers

A four-band carbon-film resistor has the color bands in the following sequence: Blue, Gray, Brown, and Gold. What is the nominal resistance value and tolerance rating of this resistor?

  1. A
    68 Ω with ±5% tolerance68\ \Omega\text{ with } \pm 5\%\text{ tolerance}
  2. B
    6.8 kΩ with ±5% tolerance6.8\text{ k}\Omega\text{ with } \pm 5\%\text{ tolerance}
  3. 680 Ω with ±5% tolerance680\ \Omega\text{ with } \pm 5\%\text{ tolerance}Answer
  4. D
    680 Ω with ±10% tolerance680\ \Omega\text{ with } \pm 10\%\text{ tolerance}

Answer

680 Ω with ±5% tolerance680\ \Omega\text{ with } \pm 5\%\text{ tolerance}
Decoding the four color bands in order yields: first band (Blue) = 6, second band (Gray) = 8, third band (Brown) = ×101\times 10^1 (1010), and fourth band (Gold) = ±5%\pm 5\%. Calculating 68×1068 \times 10 gives a nominal resistance of 680 Ω680\ \Omega with ±5%\pm 5\% tolerance.

Step-by-Step Solution

1
Identify the significant digits from the first two color bands
Blue corresponds to the digit 6 and Gray corresponds to the digit 8, forming the significant number 68.
In a standard four-band resistor, the first two bands represent the first and second significant digits of the resistance value.
2
Determine the multiplier from the third color band and calculate the nominal resistance
Brown corresponds to a multiplier of 10110^1 (1010). Multiplying 68×10=680 Ω68 \times 10 = 680\ \Omega.
The third band indicates the power of ten by which the significant digits are multiplied.
3
Identify the tolerance percentage from the fourth color band
Gold corresponds to a tolerance of ±5%\pm 5\%.
The fourth band indicates the manufacturing tolerance of the resistor.

Key Concept

Four-band resistor color code decoding
Estimated Time:35s
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Topics

Resistors and Potentiometers

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