The potentiometer is an ……as if measures the emf of a cell very accurately

Answer

To solve the question, we need to determine what the potentiometer is in the context of measuring the emf (electromotive force) of a cell accurately.

### Step-by-Step Solution:

1. **Understanding the Potentiometer**:
- A potentiometer is an instrument used to measure the potential difference (voltage) across two points in a circuit. It operates on the principle of comparing the unknown voltage with a known reference voltage.

2. **Functionality of the Potentiometer**:
- The potentiometer works by balancing the unknown voltage against a known voltage. When the two voltages are equal, the current through the potentiometer wire is zero, allowing for a precise measurement of the unknown voltage.

3. **Accuracy in Measurement**:
- The potentiometer is considered to be an ideal voltmeter because it does not draw any current from the circuit when measuring voltage. This characteristic allows it to measure the emf of a cell without affecting the circuit, leading to very accurate readings.

4. **Conclusion**:
- Therefore, the statement can be completed as: "The potentiometer is an **ideal voltmeter** as it measures the emf of a cell very accurately."

### Final Answer:
The potentiometer is an **ideal voltmeter** as it measures the emf of a cell very accurately.

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