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Question

The color code for a 47 Ω resistor with 1% tolerance would be: 

The correct answer is yellow, violet, black, brown

Resistor Color Code Fundamentals

The color code system is used to identify the resistance value, tolerance, and sometimes the temperature coefficient of a resistor. Resistors typically have 4, 5, or 6 color bands. For the given problem, we assume a 4-band resistor as it's common for indicating resistance and tolerance.

Here's how the color bands are interpreted for a 4-band resistor:

  • First Band: Represents the first significant digit of the resistance value.
  • Second Band: Represents the second significant digit of the resistance value.
  • Third Band: Represents the decimal multiplier. This indicates how many zeros follow the significant digits.
  • Fourth Band: Represents the tolerance of the resistor, indicating the permissible variation from its stated resistance value.

Understanding the standard color code values is crucial. Here is a table summarizing the common color code values for digits, multipliers, and tolerance:

Color Digit Multiplier Tolerance
Black 0 \(10^0\) (1)
Brown 1 \(10^1\) (10) \(\pm 1\%\)
Red 2 \(10^2\) (100) \(\pm 2\%\)
Orange 3 \(10^3\) (1k)
Yellow 4 \(10^4\) (10k)
Green 5 \(10^5\) (100k) \(\pm 0.5\%\)
Blue 6 \(10^6\) (1M) \(\pm 0.25\%\)
Violet 7 \(10^7\) (10M) \(\pm 0.1\%\)
Gray 8 \(10^8\) (100M)
White 9 \(10^9\) (1G)
Gold \(10^{-1}\) (0.1) \(\pm 5\%\)
Silver \(10^{-2}\) (0.01) \(\pm 10\%\)
None \(\pm 20\%\)

Decoding 47 Ω Resistor Color

We need to find the color code for a 47 Ω resistor with 1% tolerance. Let's break down the value:

Resistance Value: 47 Ω

  • First Digit (4): According to the color code table, the digit '4' corresponds to the color Yellow. This will be our first band.
  • Second Digit (7): The digit '7' corresponds to the color Violet. This will be our second band.
  • Multiplier: To get 47 Ω from the digits 4 and 7, we need a multiplier of \(10^0\), which is 1. The color corresponding to a multiplier of \(10^0\) is Black. This will be our third band.

Tolerance: 1%

  • The color corresponding to a tolerance of \(\pm 1\%\) is Brown. This will be our fourth band.

Therefore, the color code for a 47 Ω resistor with 1% tolerance is Yellow, Violet, Black, Brown.

Option Analysis

Let's evaluate the given options based on our derived color code:

  • 1. yellow, blue, black, black:
    • Yellow = 4
    • Blue = 6
    • Black = \(10^0\) (Multiplier)
    • Black (Tolerance) = This is not a standard tolerance color for 4-band resistors, often implies 20% or not specified.
    • Resulting value: \(46 \times 10^0 = 46\) Ω. Tolerance is not 1%. This option is incorrect.
  • 2. yellow, green, brown, gold:
    • Yellow = 4
    • Green = 5
    • Brown = \(10^1\) (Multiplier)
    • Gold = \(\pm 5\%\) (Tolerance)
    • Resulting value: \(45 \times 10^1 = 450\) Ω. Tolerance is 5%. This option is incorrect.
  • 3. yellow, blue, brown, silver:
    • Yellow = 4
    • Blue = 6
    • Brown = \(10^1\) (Multiplier)
    • Silver = \(\pm 10\%\) (Tolerance)
    • Resulting value: \(46 \times 10^1 = 460\) Ω. Tolerance is 10%. This option is incorrect.
  • 4. yellow, violet, black, brown:
    • Yellow = 4
    • Violet = 7
    • Black = \(10^0\) (Multiplier)
    • Brown = \(\pm 1\%\) (Tolerance)
    • Resulting value: \(47 \times 10^0 = 47\) Ω. Tolerance is 1%. This option matches our derived color code perfectly.

Based on the detailed analysis, the color code yellow, violet, black, brown correctly represents a 47 Ω resistor with 1% tolerance.

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Important Questions from Circuit Elements - Teaching

  1. 2 resistors of 4 ohm each are connected in series. What is their equivalent resistance?

  2. A lead wire and an iron wire are connected in parallel. Their respective specific resistances are in the ratio 40 ∶ 20. The former carries 80% more current than the latter, and the latter is 45% longer than the former. Determine the ratio of their cross-sectional areas latter to former.

  3. The resistor which is nonlinear in nature is called as:

  4. The resistances in the higher range are mostly made of: 

  5. A 100 Ω  resistor has a conductance of:

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