Four identical charges +50μCeach are placed, one at each corner of a square of side 2m. How much external energy is required to bring another charge of+50μCfrom infinity to the centre of the square(Given14πϵ0=9×109Nm2C2)
A
64 J
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B
41 J
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C
16 J
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D
10 J
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Solution
The correct option is A 64 J Potential at the centre of square V=4×(9×109×50×10−6√2)=90√2×104V Work done in bringing a charge (q = 50μC) from∞to centre (O) of the square is W=q(V0−V∞)=qV0 ⇒W=50×10−6×90√2×104=64J