Question

A conductor has been given a charge $ -3 \times 10^{-7} $ by transferring electrons. Mass increase (in $ kg $ ) of the conductor and the number of electrons added to the conductor are respectively

• A. $ 2 \times 10^{-16} $ and $ 2 \times 10^{31} $
• B. $ 5 \times 10^{-31} $ and $ 5 \times 10^{19} $
• C. $ 3 \times 10^{-19} $ and $ 9 \times 10^{16} $
• D. $ 2 \times 10^{-18} $ and $ 2 \times 10^{12} $

Answer 1

Answer: (D)

Number of electrons added to the conductor
$n=\frac{q}{e}$
$=\frac{-3\times10^{-7}}{1.6\times10^{-19}}=1.8\times10^{12}$
Mass increase of the conductor
$=1.8\times10^{12}\times9.1\times10^{-31}$
$=20\times10^{-19}=2\times10^{-18}$