JEE Main & Advanced Physics Electrostatics & Capacitance Question Bank Electric Field and Potential

  • question_answer
    The displacement of a charge Q in the electric field \[E={{e}_{1}}\hat{i}+{{e}_{2}}\hat{j}+{{e}_{3}}\hat{k}\] is \[\hat{r}=a\hat{i}+b\hat{j}\]. The work done is                                                                                [EAMCET (Engg.) 2000]

    A)            \[Q(a{{e}_{1}}+b{{e}_{2}})\]

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

    C)            \[Q({{e}_{1}}+{{e}_{2}})\sqrt{{{a}^{2}}+{{b}^{2}}}\]

    D)                                      \[Q(\sqrt{e_{1}^{2}+e_{2}^{2})}\ (a+b)\]

    Correct Answer: A

    Solution :

                         By using  \[W=Q\,(\overrightarrow{E}.\Delta \overrightarrow{r\,})\] Þ\[W=Q\,[({{e}_{1}}\hat{i}+{{e}_{2}}\hat{j}+{{e}_{3}}\hat{k}).(a\hat{i}+b\hat{j})]=Q\,({{e}_{1}}a+{{e}_{2}}b)\]


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