Electrostatics

JEE Main level, single correct, medium

271 of 311

Question 271 of 311

A point charge causes an electric flux of −2×104Nm2C−1-2 \times 10^4 \mathrm{Nm}^2 \mathrm{C}^{-1} to pass through a spherical Gaussian surface of 8.0 cm radius, centred on the charge. The value of the point charge is :
(Given ϵ0=8.85×10−12C2 N−1 m−2\epsilon_0=8.85 \times 10^{-12} \mathrm{C}^2 \mathrm{~N}^{-1} \mathrm{~m}^{-2} )

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Answer: (D) −17.7×10−8C-17.7 \times 10^{-8} \mathrm{C}

 Flux (ϕ)=θinc ϵ0θinc =ϵ0ϕ=−17.7×10−8C\begin{aligned} & \text { Flux }(\phi)=\frac{\theta_{\text {inc }}}{\epsilon_0} \\ & \begin{aligned} \theta_{\text {inc }} & =\epsilon_0 \phi \\ \quad= & -17.7 \times 10^{-8} \mathrm{C}\end{aligned}\end{aligned}

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