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Formula Used:
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The Fraction Value refers to the fraction of the full-scale reading displayed on the instrument's scale. It's a fractional part of the maximum resistance range that the ohmmeter can measure, calculated based on the unknown resistance and the meter's internal resistance.
The calculator uses the formula:
Where:
Explanation: This formula calculates the fraction of full-scale current for a shunt type ohmmeter by comparing the unknown resistance to the total resistance in the circuit.
Details: Accurate calculation of the fraction value is crucial for proper calibration of ohmmeters, ensuring accurate resistance measurements, and understanding the instrument's scale readings.
Tips: Enter unknown resistance and meter resistance in ohms. Both values must be positive numbers greater than zero for accurate calculation.
Q1: What does the fraction value represent?
A: The fraction value represents the proportion of full-scale current that flows through the meter when measuring an unknown resistance.
Q2: How does meter resistance affect the measurement?
A: Higher meter resistance reduces the fraction value for a given unknown resistance, affecting the sensitivity and accuracy of the measurement.
Q3: What are typical values for meter resistance?
A: Meter resistance varies by instrument type but typically ranges from a few ohms to several hundred ohms depending on the ohmmeter design.
Q4: Can this formula be used for all types of ohmmeters?
A: This specific formula applies to shunt-type ohmmeters. Other ohmmeter types may use different calculation methods.
Q5: How accurate is this calculation?
A: The calculation is mathematically precise. Accuracy in practical applications depends on the precision of the resistance values used.