Question

Ratio of the electrostatic to gravitational force between two electrons placed at a certain distance in air will be ($m_e$ = $9.1\times 10$${}^{-31}kg$, $e=1.6\times 10$${}^{-19}C$ and $G=6.6\times 10$${}^{-11}$ $N{m}^2/k{g}^2$):

• A. $4.2\times {10}^{42}$
• B. $4.2\times {10}^{-42}$
• C. $2.4\times {10}^{24}$
• D. $2.4\times {10}^{-24}$

Answer 1

The correct option is A $4.2\times {10}^{42}$

$F_g=(G\times m^2)/r^2$

$F_e=(K\times e^2)/r^2$

$F_e/F_g=(K\times e^2)/(G\times m^2)$

$=\frac{[9\times {10}^9\times (1.6\times {10}^{-19}{)}^2]}{[6.6\times {10}^{-11}\times (9.1\times {10}^{-31}{)}^2]}$

$=4.2\times {10}^{42}$