An electron and a positron are separated by distance r. Find the ratio of the gravitational force to the electric force between them. From the result, what can you conclude concerning the forces acting between particles detected in a bubble chamber?

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Allyson Vance · Accepted Answer

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      The ratio of the gravitational force to the electric force thus becomes            F      g              F      e        =            (      6.67      ×              10                  −          11                           N              m        2                    /                    C        2            )      (      9.1      ×              10                  −          31                           k      g              )        2                    (      9      ×              10        9                   N              m        2                    /                    C        2            )      (      1.6      ×              10                  −          19                           C              )        2                =  2.4  ×      10          −      43      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. Find the ratio of the gravitational force to the electric force between them. From the result, what can you conclude concerning the forces acting between particles detected in a bubble chamber?

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