Electrostatics

JEE Main level, numerical answer, medium

35 of 311

Question 35 of 311

Two identical conducting spheres with negligible volume have 2.1nC2.1nC and −0.1nC-0.1nC charges, respectively. They are brought into contact and then separated by a distance of 0.5m0.5m. The electrostatic force acting between the spheres is ___×10−9N\times {10}^{-9}N.
[Given : 4πϵ0=19×1094\pi {\epsilon }_{0}=\dfrac{1}{9\times {10}^{9}} SI unit]

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Answer: 36

q=(2.1−0.1)2nC=1nCq=\dfrac{\left(2.1-0.1\right)}{2}nC=1nC
f=9×109×10−18(0.5)2=36×10−9f=\dfrac{9\times {10}^{9}\times {10}^{-18}}{{\left(0.5\right)}^{2}}=36\times {10}^{-9}

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