Join the Most Relevant JEE Main 2025 Test Series & get 99+ percentile! Join Now
Search any question & find its solution
Question: Answered & Verified by Expert
A cubical region of side $a$ has its centre at the origin. It encloses three fixed point charges, $-q$ at $(0,-a / 4,0),+3 q$ at $(0,0,0)$ and $-q$ at $(0,+a / 4,0)$. Choose the correct options(s)


PhysicsElectrostaticsJEE AdvancedJEE Advanced 2012 (Paper 1)
Options:
  • A The net electric flux crossing the plane $x=+a / 2$ is equal to the net electric flux crossing the plane $x=-$ $a / 2$
  • B The net electric flux crossing the plane $y=+a / 2$ is more than the net electric flux crossing the plane $y=-a / 2$.
  • C The net electric flux crossing the entire region is $\frac{q}{\varepsilon_{0}}$
  • D The net electric flux crossing the plane $z=+a / 2$ is equal to the net electric flux crossing the plane $x=+a / 2$.
Solution:
2939 Upvotes Verified Answer
The correct answers are: The net electric flux crossing the plane $x=+a / 2$ is equal to the net electric flux crossing the plane $x=-$ $a / 2$, The net electric flux crossing the entire region is $\frac{q}{\varepsilon_{0}}$, The net electric flux crossing the plane $z=+a / 2$ is equal to the net electric flux crossing the plane $x=+a / 2$.
Due to symmetry, the net electric flux passing through $x=+\frac{a}{2}$, $x=-\frac{a}{2}, z=+\frac{a}{2}$ is same

According to Gauss's theorem, net electric flux net electric flux crossing through any closed surface $\phi=\frac{q_{\text {in }}}{\varepsilon_{0}}=$ $\frac{-q+3 q-q}{\varepsilon_{0}}=\frac{q}{\varepsilon_{0}}$.

Looking for more such questions to practice?

Download the MARKS App - The ultimate prep app for IIT JEE & NEET with chapter-wise PYQs, revision notes, formula sheets, custom tests & much more.