Two fixed charges A and B of 5 micro coulomb each are separated by a distance of 6m C - Physics - Electric Charges And Fields

Question

Two fixed charges A and B of 5 micro coulomb each are separated by
a distance of 6m C is the mid point of line joining A and B A
charge Q of -5microcoulomb is shot perpendicular to the line
joining A and B through C with a kinetic energy of 0 06 J The
charge Q comes to rest at a point D Find distance CD

Apurba Paul · Accepted Answer

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Here the charge will be stopped when the increase in potentialenergy will be same as initial kinetic energy
 Now the potentialenergy of Q at C is 14πε0qQ3×2 (suppose other two charges are q)Now potential of Q at D is 14πε0qQr×2
 Hence the difference in potential energy is 2qQ4πε013-1r=0
4513-1rHence we have0 4513-1r=0
06r=5mNow r = AC2+CD2=32+CD2=5⇒CD=4mHence D) is correct answer