Resistor Value Formula:
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Definition: This calculator determines the resistance value and tolerance range of a 4-band color-coded resistor.
Purpose: It helps electronics engineers, technicians, and hobbyists quickly identify resistor values without memorizing the color code.
The calculator uses the formula:
Where:
Explanation: The first two bands represent digits, the third band is the multiplier (power of 10), and the fourth band indicates tolerance.
Details: Color coding allows for easy identification of resistor values when printed numbers would be too small to read. Understanding these codes is essential for circuit design and troubleshooting.
Tips: Select the color for each band from the dropdown menus. The calculator will display the resistance value and tolerance range.
Q1: What if my resistor has 5 or 6 bands?
A: This calculator is for 4-band resistors only. 5-band resistors have three significant digits, and 6-band resistors include a temperature coefficient.
Q2: Why are gold and silver used for multipliers?
A: Gold (×0.1) and silver (×0.01) are used for values less than 1 ohm (e.g., 0.1Ω, 0.01Ω).
Q3: What does tolerance mean?
A: Tolerance indicates how much the actual resistance may vary from the marked value (e.g., ±5% for gold).
Q4: How do I read the resistor bands?
A: Hold the resistor with the tolerance band (usually gold or silver) to the right. Read bands left to right.
Q5: What's the most common resistor tolerance?
A: 5% (gold) is most common for general purpose resistors, while precision resistors may have 1% (brown) or better.