Potentiometer
A potentiometer wire of length 10 m has a resistance of 20 Ω. If a cell of EMF 2 V is balanced at 400 cm, what is the potential gradient?
Select the correct option:
Solution
0.5 V/m
- Concept: Potentiometer works on the principle that the potential drop across a segment of wire is directly proportional to its length (E=k⋅l).
- Formulate Potential Gradient (k): k=E/l.
- Identify Balanced State: The cell of 2 V is perfectly balanced by the potential drop of a 400 cm (4 m) segment.
- Calculation:
- k=4 m2 V
- k=0.5 V/m.
- Note: The gradient remains constant for the entire wire as long as the primary circuit current is steady.
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About This Question
- Subject
- physics
- Chapter
- current electricity
- Topic
- potentiometer
- Difficulty
- Medium
- Year
- 2025
Solution
Correct Answer:
0.5 V/m
- Concept: Potentiometer works on the principle that the potential drop across a segment of wire is directly proportional to its length (E=k⋅l).
- Formulate Potential Gradient (k): k=E/l.
- Identify Balanced State: The cell of 2 V is perfectly balanced by the potential drop of a 400 cm (4 m) segment.
- Calculation:
- k=4 m2 V
- k=0.5 V/m.
- Note: The gradient remains constant for the entire wire as long as the primary circuit current is steady.
This medium difficulty physics question is from the chapter current electricity, covering the topic of potentiometer. It appeared in the 2025 exam.
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