Two point charges of 1 nC and 2 nC are placed at the two corners of equilateral triangle of side 3 cm. The work done in bringing a charge of 3 nC from infinity to the third corner of the triangle is ____ μJ. 4πϵ01=9×109N.m2/C2
(A)2.7✓ Correct
(B)5.4
(C)3.3
(D)27
Answer: (A)
Solution
Work done = potential energy at the third corner.
W=q3(ℓkq1+ℓkq2)
where ℓ=3cm=0.03m, q1=1nC, q2=2nC, q3=3nC.
W=0.039×109×(1+2)×10−9×3×10−9
W=3×1011×3×3×10−18=27×10−7J=2.7μJ
JEE Main · 2026 · 28 Jan 2026 · Shift 1 · Single correct option