Question

Name two factors on which the internal resistance of a cell depends.
A.)Separation between plates
B.)Emf of cell
C.)Area of plates
D.)External resistance

Answer 1

Hint: Recall the relation between resistivity and resistance of a cell.
\[(R=\rho \dfrac{l}{A})\] . The resistivity depends directly on the distance between the electrodes (l) and inversely upon the cross sectional area of the electrode (A).

Complete step by step answer:

The resistance of an electrolytic cell is a measure of the opposition offered by the cell to electric current passing through it when a potential difference is applied to it.
\[(R=\rho \dfrac{l}{A})\]

The resistance of an electrolytic cell depends on a number of factors. It is directly proportional to the separation between its plates and inversely proportional to the area of its plates, temperature and concentration of the electrolyte.
Where R is the resistance of the cell, l is the separation between the plates, A is the area of the plates and ρ is the specific resistance or resistivity of the electrolyte.
The resistance of an electrolytic cell is measured in Ohm (Ω).

So, the correct answers are A) separation between plates and C) area of plates.

Additional information: The opposite of resistance is conductance (G). It is a measure of how easily current passes through the electrolytic cell. It is the inverse of resistance, i.e.
$G=\dfrac{1}{R}$
The conductance is measured in mho (ohm-1) or Siemen.
Similarly, the specific conductance or conductivity (κ) is the inverse of resistivity, i.e.
$\kappa =\dfrac{1}{\rho }$
Conductivity is measured in mho m-1 or Siemen-metre inverse (Sm-1).

Note: Students may be tempted to think that the separation between plates do not have an effect on the resistance of an electrolytic cell, as they may think that the liquid electrolyte anyway occupies the whole length of the cell which is almost always more than the separation between the plates.

However, this is not true, as electric current primarily flows only in the part of the electrolyte between the two plates.