Question

three charges +q,+q or -q are placed on the circumference of a circle of radius r. The force on charge +Q placed at the center of the circle​

Answer 1

Explanation:

I hope this helps, by the way, here when two equal forces act on a single particle, then the resultant force will be in the middle

Answer 2

• We know that,

         I$f_{1}$I $=$ I$f_{2}$I $=f$

• The basic  formula used  for force on a cahrged particle is,

                  I$f=\frac{kqQ}{r^{2} }$  ,      $Q=120$

• The formula ued to calculate resultant,

                   $f_{R} =\sqrt{f_{1} ^{2}+ f_{2} ^{2} } +\sqrt{2f_{1} f_{2} }$cosθ

                        $=\sqrt{2f^{2}+2f^{2}(\frac{-1}{2}) }$

                  I$f_{R}$I $=\sqrt{2f^{2} -f^{2} }$

                  I$f_{R}$I  $=$ I$F$I

• also $f_{3}$ is along $f_{R}$,

• therefore net force = $f_{R} +f_{3}$

             $F_{net} =\frac{kqQ}{r^{2} } + \frac{kqQ}{r^{2} }$

                      $=2F_{}$