Resistor Value Calculator
Resistor Value Calculator
A resistor value calculator determines the resistance of a resistor based on its color bands. By inputting the colors of the first, second, and third bands (representing significant digits and the multiplier) and optionally the fourth band (tolerance), the calculator computes the resistor’s nominal resistance and tolerance.
What is Resistor Color Value?
The resistor color code is a system used to indicate the value of a resistor using colored bands. Each color represents a specific digit or multiplier. The standard color codes are:
1. Black: 0
2. Brown: 1
3. Red: 2
4. Orange: 3
5. Yellow: 4
6. Green: 5
7. Blue: 6
8. Violet: 7
9. Gray: 8
10. White: 9
The resistor color code typically uses four bands:
1. First Band: First digit
2. Second Band: Second digit
3. Third Band: Multiplier (power of ten)
4. Fourth Band (Tolerance): Accuracy (optional)
Formula for Calculating Resistor Value
\[ R = (D_1 \times 10 + D_2) \times 10^M \]
where:
– \( D_1 \) is the digit represented by the first color band.
– \( D_2 \) is the digit represented by the second color band.
– \( M \) is the multiplier represented by the third color band (0 for black, 1 for brown, 2 for red, etc.).
Example
Assume a resistor has the color bands: Red, Red, Brown, and Gold.
1. Red (First Band): 2
2. Red (Second Band): 2
3. Brown (Multiplier): \( 10^1 \)
4. Gold (Tolerance): ±5% (not used in the calculation of resistance value)
Using the formula:
\[ R = (2 \times 10 + 2) \times 10^1 \]
\[ R = (20 + 2) \times 10 \]
\[ R = 22 \times 10 \]
\[ R = 220 \, \Omega \]
The resistor value is 220 ohms with a tolerance of ±5%.
