Q.

Three point charges q, -2q and 2q are placed on the x-axis at distances x=0, x=34R and x=R respectively from the origin, as shown. If q=2×10-6 C and R=2 cm, the magnitude of the net force experienced by the charge -2q is _______ N.                    [2023]


Ans.

(5440)

FBA=Kq(2q)(34R)2=32Kq29R2

FBC=K(2q)(2q)(R4)2=64Kq2R2

FB=FBC-FBA=544Kq29R2

=544×9×109×(2×10-6)29×(2×10-2)2=5440 N