Question

The ratio of magnitude of electrostatic force and gravitational force for an electron and a proton is

• A. $6.6\times 10^{39}$
• B. $2.4\times 10^{39}$
• C. $6.6\times 10^{29}$
• D. $2.4\times 10^{29}$

Answer 1

Answer: (B)

Here, for an electron and a proton Electrostatic force, $\left|F_e\right|=\frac{1}{4\pi {\epsilon }_0}\frac{e^2}{r^2}$
Gravitational force, $\left|F_g\right|=\frac{G{m}_e{m}_p}{r^2}$
$\therefore \frac{|F_e|}{|F_g|}=\frac{1}{4\pi {\epsilon }_0}\frac{e^2}{G{m}_e{m}_p}$
$=\frac{9\times 10^9\times {\left(1.6\times 10^{-19}\right)}^2}{6.67\times 10^{-11}\times 9\times 10^{-31}\times 1.66\times 10^{-27}}$
$=2.4\times 10^{39}$