Question

A number of condensers, each of the capacitance $1\mu F$ and each one of which gets punctured if a potential difference just exceeding $500V$ is applied, are provided. An arrangement suitable for giving capacitance of $2\mu F$ across which $3000V$ may be applied requires at least

• A. 6 component capacitors
• B. 12 component capacitors
• C. 72 component capacitors
• D. 2 component capacitors

Answer 1

Answer: (C)

Minimum number of condensers in each row
$=\frac{3000}{500}=6$
If $C$, is capacity of $6$ condensers in a row,
$\frac{1}{C_s}=\frac{1}{1}+\frac{1}{1}+\frac{1}{1}+\frac{1}{1}+\frac{1}{1}+\frac{1}{1}=6$
$C_s=\frac{1}{6}\mu F$
Let there be $m$ such rows in parallel,
Total capacity $=m\times C_s$
$2=m\times \frac{1}{6}$
$\therefore m=12$
Total number of capacitors $=6\times 12$
$=72$