Two cells of emfs approximately 5V and 10V are to be accurately compar...
In a potentiometer experiment, the Emf of a cell can be measured if the potential drop along the potentiometer wire is more than the emf to be determined. As values of emfs is of two cells are approximately 5 V and 10 V. There fore the potential drop along the potentiometer wire must be more than 10 V. So option (b) is correct.
View all questions of this test
Two cells of emfs approximately 5V and 10V are to be accurately compar...
Explanation:
The correct answer is option 'B' - The battery of the potentiometer can have a voltage of 15V and R adjusted, so that the potential drop across the wire slightly exceeds 10V.
Reasoning:
To accurately compare the emfs of two cells using a potentiometer, we need to ensure that the potential drop across the wire is slightly greater than the larger emf (10V in this case). This is because the potentiometer works by comparing the potential drops across different lengths of the wire.
Explanation in Detail:
A potentiometer is a device used to measure an unknown voltage by comparing it with a known voltage. It consists of a long wire of uniform cross-section, a battery, a galvanometer, and a jockey or sliding contact. The wire is usually made of a material with high specific resistance, such as constantan.
The potentiometer works on the principle of a voltage divider. The potential drop across a length of the wire is directly proportional to its length. By adjusting the position of the jockey, we can compare the potential drops across different lengths of the wire.
In this question, we are comparing two cells of emfs approximately 5V and 10V using a potentiometer of length 400 cm. To accurately compare the emfs, we need to ensure that the potential drop across the wire is slightly greater than the larger emf (10V).
Option A suggests using a battery with a voltage of 8V. This would not give us a potential drop greater than 10V, so it is not the correct answer.
Option B suggests using a battery with a voltage of 15V and adjusting the resistance (R) so that the potential drop across the wire slightly exceeds 10V. This is the correct answer because it allows us to create a potential difference greater than 10V, which is necessary for accurate comparison.
Option C suggests that the first portion of 50 cm of wire itself should have a potential drop of 10V. This would not allow us to accurately compare the two cells since the potential drop across the wire needs to be slightly greater than 10V.
Option D states that a potentiometer is usually used for comparing resistances and not voltages. This statement is incorrect because a potentiometer can be used to compare both resistances and voltages. In this case, we are using it to compare the emfs of two cells.
Therefore, the correct answer is option B - The battery of the potentiometer can have a voltage of 15V and R adjusted, so that the potential drop across the wire slightly exceeds 10V.
Two cells of emfs approximately 5V and 10V are to be accurately compar...
Correct answer is option.B
To make sure you are not studying endlessly, EduRev has designed NEET study material, with Structured Courses, Videos, & Test Series. Plus get personalized analysis, doubt solving and improvement plans to achieve a great score in NEET.