Question

A capacitor acquires a potential difference of $200V$ when ${10}^{12}$ electrons are taken from one plate and placed on the other plate. Its capacitance is:

• A. $2\times {10}^{-10}F$
• B. $4\times {10}^{-10}F$
• C. $8\times {10}^{-10}F$
• D. $12\times {10}^{-10}F$

Answer 1

Answer: (C)

$8\times {10}^{-10}F$

Charge acquired when ${10}^{12}$ electron are taken:
$Q={10}^{12}\times 1.6\times {10}^{-19}$

We known $Q=CV$
or, $C=\frac{Q}{V}$
or, $C=\frac{1.6\times {10}^{-7}}{200}F$$=8\times {10}^{-10}F$