A battery of e.m.f. 10 V and internal resistance `2 Omega` is connected in primary circuit with a uniform potentiometer wire and a rheostat whose resistance is fixed at `998 Omega`.A battery of unknown e.m.f. is being balanced on this potentiometer wire and balancing length is found to be 50 cm.When area of cross section of potentiometer wire is doubled, then balancing length is found to be 75 cm.
(i)Calculate e.m.f. of the battery.
(ii)Calculate resistivity of potentiometer wire if length of wire is 100 cm and area of cross-section (initially) is `100 cm^2`.

Answer

(a)2.5 volt , (b)`10 Omega-m`