Question

A $10m$ long potentiometer wire is connected to a battery having a steady voltage. A Leclanche cell is balanced at $4m$ length of the wire. If the length is kept the same, but its cross-section is doubled, the null point will be obtained at:

• A. $8m$
• B. $4m$
• C. $2m$
• D. None of these

Answer 1

The correct option is B $4m$

If lemgth of potentiometer is same, null point will obtained at some point because potential gradient will not change.

Potential gradient $=\frac{V}{L}$

V=Voltage across potentiometer

L=length of potentiometer wire

Now in question,

Null point will not change and will be obtained at $4m$