Question

Two voltameters, one of copper and another of silver, are joined in parallel. When a total charge q flows through the voltameters, equal amount of metals are deposited. If the electrochemical equivalents of copper and silver are $z_{1}$ and $z_{2}$ respectively the charge which flows through the silver voltameter is

• A. $q\frac{z_{1}}{z_{2}}$
• B. $q\frac{z_{2}}{z_{1}}$
• C. $\frac{q}{1 + \frac{z_{1}}{z_{2}}}$
• D. $\frac{q}{1 + \frac{z_{2}}{z_{1}}}$

Answer 1

Answer: (D)

$\frac{q}{1 + \frac{z_{2}}{z_{1}}}$

Answer 2

$m = zq$ ⇒ $z \propto \frac{1}{q}$ ⇒ $\frac{z_{1}}{z_{2}} = \frac{q_{2}}{q_{1}}$ ......(i)

also $q = q_{1} + q_{2}$ ⇒ $\frac{q}{q_{2}} = \frac{q_{1}}{q_{2}} + 1$

⇒ $q_{2} = \frac{q}{1 + \frac{q_{1}}{q_{2}}}$ ......(ii)

From equation (i) and (ii) $q_{2} = \frac{q}{1 + \frac{z_{2}}{z_{1}}}$