Question

If the value of the potential gradient on the potentiometer wire is decreased, then the new null point will be obtained at

• A. lower length
• B. higher length
• C. same length
• D. nothing can be said

Answer 1

Answer: (B)

higher length

Answer 2

The correct answer is option (B) : higher length

The potential gradient on a potentiometer wire is defined as the rate of change of potential per unit length of the wire. When the potential gradient is decreased, it means that the change in potential per unit length becomes smaller. In a potentiometer, the null point is the point where the potential difference across the length of the wire is equal to the potential difference across the given emf cell (or battery). At the null point, the galvanometer shows zero deflection, indicating that there is no potential difference between the two ends of the wire. When the potential gradient is decreased, it implies that the potential difference per unit length is smaller. This means that for the same potential difference across the emf cell, the length of the wire required to achieve the null point will be longer. In other words, the null point will be obtained at a higher length on the potentiometer wire. Therefore, the correct answer is option B. higher length.