An electron and a positron are separated by distance r. Findthe ratio of the gravitational force to the electric force betweenthem. From the result, what can you conclude concerning theforces acting between particles detected in a bubble chamber?(Should gravitational interactions be considered?)

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Ariella Bruce · Accepted Answer

Answer for part (a)The gravitational force in this case is      F    g    =            G              m        e        2                    r      2          =            (      6.67      ×              10                  −          11                    N              m        2                    /                    C        2            )      (      9.1      ×              10                  −          31                    k      g              )        2                    r      2      The electrical force between the electron-positron pair is      F    e    =            k              e        2                    r      2          =            (      9      ×              10        9            N              m        2                    /                    C        2            )      (      1.6      ×              10                  −          19                    C              )        2                    r      2      Answer for part (a) continuesThe ratio of the gravitational force to the electric force thus becomesfrac{F_g}{F_e}=frac{(6.67 times 10^{-11} Nm^2/C^2)(9.1 times 10^{-31}kg)^2}{(9 times 10^9 Nm^2/C^2)(1.6 times 10^{-19}C)^2}=2.4 times 10^{-43}Answer for part (b)It can be observed that       F    g    &amp;lt;&amp;lt;&amp;lt;&amp;lt;&amp;lt;      F    e  . Therefore, the gravitational force can be ignored in a bubble chamber where the electron-positron pair is detected.

An electron and a positron are separated by distance r.

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