Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
NEET 2026
Exam
NEET
Year
2026
Subject
Physics
Chapter
Chapter

NEET 2026 · Physics · Chapter

A closed Gaussian surface contains no net charge, while some point...

A closed Gaussian surface contains no net charge, while some point charges are situated outside it. Which of the following is a correct deduction regarding the electric field E⃗\vec{E} and the net electric flux Φ\Phi through the surface?

Options

  1. AThe electric field E⃗\vec{E} must be zero at all points on the surface.
  2. BThe net electric flux Φ\Phi is zero, but E⃗\vec{E} at the surface need not be zero.
  3. CThe external charges will produce a non-zero net electric flux Φ\Phi through the surface.
  4. DThe electric field E⃗\vec{E} at any point on the surface is independent of the external charges.

Correct answer

B. The net electric flux Φ\Phi is zero, but E⃗\vec{E} at the surface need not be zero.

Step-by-step solution

According to Gauss's Law, the net electric flux through a closed surface is given by Φ=∮E⃗⋅dA⃗=qinϵ0\Phi = \oint \vec{E} \cdot d\vec{A} = \dfrac{q_{in}}{\epsilon_0}.

Since the net charge enclosed by the Gaussian surface is zero (qin=0q_{in} = 0), the net electric flux Φ\Phi through the surface must be zero.

The electric field E⃗\vec{E} at any point on the surface is the resultant field due to all charges present in space, both inside and outside the surface. Since there are point charges situated outside the surface, they will produce an electric field at points on the surface. Thus, the electric field E⃗\vec{E} at the surface need not be zero, even though the net flux is zero.

Answer: The net electric flux Φ\Phi is zero, but E⃗\vec{E} at the surface need not be zero.
Practice Chapter on Quantrex Academy →

More from Chapter

A solid spherical body of radius R , density ρ , and specific heat capacity s is… NEET 2026A straight canal has motorboats departing from two terminals at opposite ends. The… NEET 2026A wooden crate is released from rest at the top of a ramp inclined at 37^ ∘ to the… NEET 2026A uniform horizontal beam of mass 6 kg and length L is hinged to a vertical wall at one… NEET 2026A bullet P of mass 30 g moving with a speed of 200 m/s penetrates a target and comes to… NEET 2026A small block of mass m is placed at the highest point of a smooth fixed sphere of radius… NEET 2026A block of mass 2 kg is projected with an initial speed of 14 m/s on a rough horizontal… NEET 2026A uniform horizontal circular disc of mass M and radius R is rotating freely about a… NEET 2026 Full Chapter list All NEET PYQs