Question

$F_G$ and $F_e$ represents gravitational and electrostatic force respectively between electrons situated at a distane $10cm$. The ratio of $F_G/F_e$ is nearly of the order of

• A. ${10}^{42}$
• B. ${10}^{-34}$
• C. $1$
• D. ${10}^{-43}$

Answer 1

The correct option is D ${10}^{-43}$

Gravitational force between electrons
$F_G=\frac{G(m_e{)}^2}{r^2}$
Electrostatic force between electrons
$F_e=k\frac{e^2}{r^2}$
$\frac{F_G}{F_e}=\frac{G(m_e{)}^2}{k{e}^2}=\frac{6.67\times {10}^{-11}\times (9.1\times {10}^{-31}{)}^2}{9\times {10}^9\times (1.6\times {10}^{-19}{)}^2}$
$=2.39\times {10}^{-43}$