Given the following colors, determine the value of the resistors using resistor color coding. a. Blue Red Brown b. Orange Brown Black Silver c. Green Yellow Orange Gold d. Violet White Green
The correct answer and explanation is:
Here are the resistor values based on the color codes:
a. Blue Red Brown
Value: 620 ohms, Tolerance: ±20% (if no fourth band is present)
b. Orange Brown Black Silver
Value: 31 ohms, Tolerance: ±10%
c. Green Yellow Orange Gold
Value: 54,000 ohms (54 kilo-ohms), Tolerance: ±5%
d. Violet White Green
Value: 7.9 mega-ohms (7,900,000 ohms), Tolerance: ±20% (if no fourth band is present)
Explanation
Resistor color coding is a method of indicating the resistance value, tolerance, and sometimes the reliability of resistors. The most common is the 4-band color code, which consists of:
- First band: first digit
- Second band: second digit
- Third band: multiplier (power of ten)
- Fourth band: tolerance
Each color corresponds to a number:
- Black = 0
- Brown = 1
- Red = 2
- Orange = 3
- Yellow = 4
- Green = 5
- Blue = 6
- Violet = 7
- Gray = 8
- White = 9
Multipliers are 10 raised to the number represented by the third color. Tolerance is shown by the fourth band:
- Gold = ±5%
- Silver = ±10%
- No band = ±20%
a. Blue Red Brown
Blue = 6, Red = 2, Brown multiplier = 10¹
So: 62 × 10 = 620 ohms
b. Orange Brown Black Silver
Orange = 3, Brown = 1, Black multiplier = 10⁰ = 1
So: 31 × 1 = 31 ohms, Tolerance = ±10%
c. Green Yellow Orange Gold
Green = 5, Yellow = 4, Orange = 10³ = 1000
So: 54 × 1000 = 54000 ohms, Tolerance = ±5%
d. Violet White Green
Violet = 7, White = 9, Green multiplier = 10⁵ = 100000
So: 79 × 100000 = 7900000 ohms or 7.9 mega-ohms
Resistor color coding helps engineers quickly read resistor values without needing to test them with a multimeter.