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The displacement of a charge Q in the electric field $E={e}_{1}\stackrel{^}{i}+{e}_{2}\stackrel{^}{j}+{e}_{3}\stackrel{^}{k}$ is $\stackrel{^}{r}=a\stackrel{^}{i}+b\stackrel{^}{j}$. The work done is

(1) $Q\left(a{e}_{1}+b{e}_{2}\right)$

(2) $Q\sqrt{{\left(a{e}_{1}\right)}^{2}+{\left(b{e}_{2}\right)}^{2}}$

(3) $Q\left({e}_{1}+{e}_{2}\right)\sqrt{{a}^{2}+{b}^{2}}$

(4) $Q\left(\sqrt{{e}_{1}^{2}+{e}_{2}^{2}\right)}\text{\hspace{0.17em}}\left(a+b\right)$