In the rectangle, shown below, the two corners have charges q1=−5μC and q2=+2.0μC. The work done in moving a charge +3.0 μC from B to A is (take 1/4πε0=1010N-m2​/C2)

Work done W=3×10−6(VA−VB); whereVA=1010(−5×10−6)15×10−2+2×10−65×10−2=115×106 voltand VB=1010(2×10−6)15×10−2−5×10−65×10−2=−1315×106 volt∴W=3×10−6115×106−−1315×106=2.8J