Question

What is the force between two electrons 1.0 centimeter apart in air?

Answer 1

$constant, k_e=9\times 10^9$

charge of electron $q_1=q_2=1.6\times 10^{-19}C$

distance, $d=1cm=0.01m$

Force, $F=\frac{k_e \times q_1 q_2}{d^2}=\frac{9\times 10^9 \times 1.6\times 10^{-19}\times1.6 \times 10^{-19}}{0.01^2}=2.304\times 10^{-24}N$