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Difficulty: MediumResistors and Potentiometers

A standard four-band through-hole resistor installed in an audio preamplifier has a specified nominal resistance of 47 kΩ47\text{ k}\Omega. If the first two color bands on the component are Yellow and Violet, what color must the third band be to indicate the correct multiplier?

  1. A
    Red
  2. OrangeAnswer
  3. C
    Yellow
  4. D
    Brown

Answer

Orange
Orange is the correct multiplier band because the significant digits from Yellow (4) and Violet (7) combine to form 47. Multiplying 47 by the Orange multiplier (10310^3 or 1,0001,000) produces 47,000 Ω47,000\ \Omega, which equals the specified 47 kΩ47\text{ k}\Omega.

Step-by-Step Solution

1
Determine the digits represented by the first two color bands.
Yellow corresponds to 4 and Violet corresponds to 7, forming the two-digit significant value 47.
In standard four-band EIA color coding, the first two bands establish the significant digits of the resistance value.
2
Convert the required resistance from kilohms into ohms.
47 kΩ=47×103 Ω=47,000 Ω47\text{ k}\Omega = 47 \times 10^3\ \Omega = 47,000\ \Omega.
The metric prefix 'kilo' represents a factor of 1,0001,000 (10310^3).
3
Calculate the multiplier and identify the corresponding band color.
47,000/47=1,000=10347,000 / 47 = 1,000 = 10^3, which corresponds to the color Orange.
The third band indicates the power-of-ten multiplier (number of trailing zeros), where Orange denotes 10310^3.

Key Concept

Standard four-band resistor color code decoding and multiplier determination
Estimated Time:40s
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Topics

Resistors and Potentiometers

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