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Difficulty: MediumResistors and Potentiometers

An electronics technician needs to replace a damaged component on a circuit board with an 820 Ω820\ \Omega resistor having a ±5%\pm 5\% tolerance. Which four-band color code sequence identifies the correct replacement resistor?

  1. A
    Gray, Red, Black, Gold
  2. Gray, Red, Brown, GoldAnswer
  3. C
    Gray, Red, Red, Gold
  4. D
    Red, Gray, Brown, Gold

Answer

Gray, Red, Brown, Gold
The color band sequence Gray, Red, Brown, Gold translates directly to 88 (Gray), 22 (Red), ×101\times 10^1 (Brown), and ±5%\pm 5\% (Gold). Multiplying the significant digits 8282 by 1010 yields exactly 820 Ω820\ \Omega with a ±5%\pm 5\% tolerance.

Step-by-Step Solution

1
Determine the first two significant digits from the target resistance value.
The first digit is 88 (Gray) and the second digit is 22 (Red).
Standard four-band resistors use the first two bands to represent significant numerical digits.
2
Calculate the multiplier needed to obtain 820 Ω820\ \Omega from the significant digits 8282.
82×101=820 Ω82 \times 10^1 = 820\ \Omega, which corresponds to the multiplier color Brown.
The third band represents the power of ten multiplier (101=1010^1 = 10, which is Brown).
3
Identify the tolerance band corresponding to ±5%\pm 5\%.
A ±5%\pm 5\% tolerance is denoted by Gold.
The fourth band indicates manufacturing tolerance, where Gold designates ±5%\pm 5\% and Silver designates ±10%\pm 10\%.

Key Concept

Four-Band Resistor Color Code Decoding
Estimated Time:40s
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Topics

Resistors and Potentiometers

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