As we know that, work done by the uniform electric field in moving a charge depends only on its final position and initial position. Displacement of charged particle in uniform electric field, r=rS−rP =(0
∧
i
+0
∧
j
+0
∧
k
)−(a
∧
i
+b
∧
j
+0
∧
k
) =−a
∧
i
−b
∧
j
∴ Work done by electric field. W=∫Fclec ⋅dr Here, Fdec=qE=qE