Question:
Potentiometer is an ideal instrument for measuring voltage because
Potentiometer is an ideal instrument for measuring voltage because
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Think of a potentiometer like a balance scale where you add weights until it's perfectly level and no one is "pushing" the scale. Because it's perfectly balanced, it provides a 100% accurate reading of the weight.
Updated On: Apr 24, 2026
- it has high resistance
- it has low resistance
- it does not draw any current from the source at null point
- it is very sensitive
- it is cheap
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The Correct Option is C
Solution and Explanation
Concept:
Physics - Electrical Measuring Instruments.
Step 1: Compare Voltmeter vs. Potentiometer.
A standard voltmeter must draw a small amount of current to move its needle or activate its sensor. This current slightly changes the potential difference it is trying to measure.
Step 2: Analyze the "Null Point" principle.
A potentiometer works on the principle of balancing an unknown EMF against a known potential difference. When the galvanometer shows zero deflection (the "null point"), no current flows between the two circuits.
Step 3: Relate to ideal measurement.
Because it draws zero current from the test source at the moment of measurement, it effectively acts as a voltmeter with infinite resistance. This allows it to measure the \textit{actual} EMF of a cell, rather than just the terminal voltage.
Step 4: Conclusion.
Its "ideal" status comes from not drawing current from the source at the null point.
Physics - Electrical Measuring Instruments.
Step 1: Compare Voltmeter vs. Potentiometer.
A standard voltmeter must draw a small amount of current to move its needle or activate its sensor. This current slightly changes the potential difference it is trying to measure.
Step 2: Analyze the "Null Point" principle.
A potentiometer works on the principle of balancing an unknown EMF against a known potential difference. When the galvanometer shows zero deflection (the "null point"), no current flows between the two circuits.
Step 3: Relate to ideal measurement.
Because it draws zero current from the test source at the moment of measurement, it effectively acts as a voltmeter with infinite resistance. This allows it to measure the \textit{actual} EMF of a cell, rather than just the terminal voltage.
Step 4: Conclusion.
Its "ideal" status comes from not drawing current from the source at the null point.
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