Random Physics - Electrostatics And Current Electricity Practice

Potentiometer is usually used for comparing resistances and not voltages.

The first portion of 50 cm of wire itself should have a potential drop of 10 V.

The battery that runs the potentiometer should have voltage of 8 V.

The battery of potentiometer can have a voltage of 15 V and $R$ adjusted so that the potential drop across the wire slightly exceeds 10 V.