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JEE Main 202529 JanuaryEvening Shift
Exam
JEE Main
Year
2025
Date
29 January
Shift
Evening Shift
Subject
Physics
Chapter
Electrostatics

JEE Main 2025 · 29 January · Evening Shift · Physics · Electrostatics

A point charge causes an electric flux of -2 × 10^4 Nm^2 C^ -1 to...

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} )

Options

  1. A15.7×10−8C15.7 \times 10^{-8} \mathrm{C}
  2. B17.7×10−8C17.7 \times 10^{-8} \mathrm{C}
  3. C−15.7×10−8C-15.7 \times 10^{-8} \mathrm{C}
  4. D−17.7×10−8C-17.7 \times 10^{-8} \mathrm{C}

Correct answer

D. −17.7×10−8C-17.7 \times 10^{-8} \mathrm{C}

Step-by-step solution

\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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