Why is it necessary to compare current density rather than current intensity at different values of applied potential to determine the efficiency of two electrodes in the same electrochemical reaction?

Kirchhoff's first law or the junction law states that: the total current entering the junction is equal to the total current leaving the junction. This follows from the conservation of charge - charge cannot be created or destroyed. As a consequence, the charge entering the junction should equal the charge leaving the junction. The scenario below: 12 1₁ 13 follows Kirchhoff's junction rule violates Kirchhoff's junction rule as there is no outgoing current cannot determine whether it follows the junction rule or not without knowing the magnitude of the currents

Problem 3: A 1.2 g wire has a density of 2.7 g/cm3 and a resistivity of 2.7 × 10−8 Ωm. The wire has a resistance of 15 Ω. a) How long is the wire? b) The wire is made up of atoms with valence 1 and molar mass 26.98 g/mol. What is the drift speed of the electrons when there is a voltage drop of 30 V across the wire?

When an electric heater is turned on, the Nichrome heating element is at 0° C and draws a current of 18 A, with a potential difference of 120 V between the ends of the element. The element heats up to 795° C, with the potential difference constant. Find the final current. (The temperature coefficient of resistivity of Nichrome is 4.0  10-4 (°C)-1.)