Q. A conductor has been given a charge $- 3 \times 10^{- 7}C$ by transferring electron. Mass increase (in $kg$) of the conductor and the number of electron 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 $2 \times 10^{12}$
Explanation
(d) Here, $q = - 3 \times 10^{- 7}C$
Number of electrons transferred to the conductor is
$n = \frac{q}{e} = \frac{- 3 \times 10^{- 7}C}{- 1.6 \times 10^{- 19}C} \approx 2 \times 10^{12}$
Mass of one electron, $m_{e} = 9.1 \times 10^{- 31}kg$
Mass increase of the conductor $= m_{e} \times n$
$= 9.1 \times 10^{- 31} \times 2 \times 10^{12} = 18.2 \times 10^{- 19}kg \approx 2 \times 10^{- 18}kg$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.