An electron is taken from point A to point B along the path AB in a uniform electric field of intensity E=10Vm−1. Side AB=5m, and side BC=3m. Then, the amount of work done on the electron by us is :
A
50 eV
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B
40 eV
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C
-50 eV
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D
-40 eV
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Solution
The correct option is B 40 eV WAB=WAC+WCB WCB should be zero, because in moving from C to B, we always move perpendicular to field. Hence, force applied by field and displacement will be at 90∘. so work done in BC will be 0 WAC=−e(VC−VA) VC−VA=−E×AC=−10×4=−40 ∴WAB=40eJ=40eV