Calculate resistivity of the material of a wire 1.0m long, 0.4mm in diameter and having a resistance of `2.0 Omega`

Calculate the length of an aluminium wire of diameter 0.4 mm required to have a resistance of 2 Omega at 20 ^@C . Resistivity of aluminium is 2.8 xx 10^-8Omegam .

The resistance of a 0.5 N solution of salt is 20 Omega .Calculate the equivalent conductance of the solution if the platinum electrodes are 1.5 cm apart and each having an area of 3.0cm^(2) .

The internal resistance of a cell of e.m.f 2V is 0.1Omega . It is connected to a resistance of 3.9Omega . The voltage across the cell will be