Tue September 27, 2011 By: Vikas Shankar


Expert Reply
Mon December 26, 2011
first: mg sin30=q2 /4??0l2  at equilibrium.
as the component of gravitational force is balanced by the electrostatic repulsion.
here the length between the centre of the two balls is 2l sin 30 =l from simple geomety,see by drawing the diagram.
now at a point which is at 2:3 dist, resultant intensity=(1/4??0)q(25/4l2 -25/9l2
putting the value of q from the first equation of equilibrium)=approximately 43.3×103N
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