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प्रश्न
Would you prefer a voltmeter or a potentiometer to measure the emf of a battery?
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उत्तर
A potentiometer is preferred to measure the emf of a battery, as it gives a more accurate result. This is because a potentiometer uses the null method to measure emf and it hardly draws any current from the primary circuit.
When a voltmeter is used in the circuit, its equivalent resistance is connected parallel to some element of the circuit. This changes the overall current in the circuit and, hence, the potential difference to be measured also changes. The error can be minimised if the equivalent resistance of the voltmeter is increased. However, we also need to keep in mind the heat dissipated due to high resistance while deciding the value of resistance of the voltmeter.
Hence a potentiometer is preferred.
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संबंधित प्रश्न
In a potentiometer experiment, balancing length is found to be 120 cm for a cell E1 of emf 2V. What will be the balancing length for another cell E2 of emf 1.5V? (No other changes are made in the experiment.)
A student uses the circuit diagram of a potentiometer as shown in the figure
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(b) What is the function of resistance R used in the circuit? How will the change in its value affect the null point?
(c) How can the sensitivity of the potentiometer be increased?
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stands for a variable resistance R′. R′ can vary from R0 to infinity. r is internal resistance of the battery (r << R << R0).
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