Question

Determine the force between two electrons at (a) 10^-10 m apart (b) 10 ^-15 m apart (c) 10 ^-20 apart .

Is the force attarctive or repulsive ? If we take a proton and electron what would be the change in the magnitude and direction of force ?

Answer 1

a)

The electrostatic force between two electron is

$F=\frac{kq^2}{r^2}=\frac{(9*10^9)(1.60*10^{-19})^2}{(10^{-10})^2}=2.304*10^{-8} N$

b)

The electrostatic force between two electron is

$F=\frac{kq^2}{r^2}=\frac{(9*10^9)(1.60*10^{-19})^2}{(10^{-15})^2}=230.4 N$

c)

The electrostatic force between two electron is

$F=\frac{kq^2}{r^2}=\frac{(9*10^9)(1.60*10^{-19})^2}{(10^{-20})^2}=2.304*10^{12} N$

Force is repulsive because both charges have same sign.

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If we take a proton and electron , then the magnitude of electrostatic force is unchanged (same as previous parts). But the direction is opposite to previous forces because sign of charge of both particles are opposite.