An electron is taken from a point \(A\) to point \(B\) along the path \(A B\) in a uniform electric field of…

An electron is taken from a point \(A\) to point \(B\) along the path \(A B\) in a uniform electric field of intensity \(E=10 \mathrm{Vm}^{-1}\), Side \(A B=5 \mathrm{~m}\) and side \(B C=3 \mathrm{~m} .\) Then, the amount of work done is (Mark answer in eV)

Solution

\(W_{A B}=W_{A C}+W_{C B}\)
\(W_{C B}\) should be zero, because in moving from \(C\) to \(B\), we always move perpendicular to the field.
Hence, force applied by field and displacement will be at \(90^{\circ}\).
\(W_{A C}=-e\left(V_{C}-V_{A}\right)\)
\(V_{C}-V_{A}=-E \times A C\)
\(=-10 \times 4=-40\)
\(W_{A C}=-e \times(-40)=40 e\)
So \(W_{A B}=40 e J=40 \mathrm{eV}\)

Asked in: JEE Mains - Electrostatics - Chapter Test

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