Choose the correct statements from the following:
(A) A dielectric develops a net dipole moment in the presence of an electric field.
(B) Electrostatic potential is constant throughout the volume of the conductor.
(C) Electric field \( \vec{E} \) depends upon the distance between two thin infinite long uniformly charged plane sheets held parallel to each other.
(D) Electric field due to a uniformly charged spherical shell is zero at all points inside the shell.
(E) Electric field is in the direction in which the potential decreases steepest.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → (A), (B), (D) and (E) only
(A) A dielectric develops a net dipole moment in the presence of an electric field. — Correct. The field polarises the dielectric: the atoms or molecules acquire (or align) dipole moments, so the slab as a whole has a net dipole moment.
(B) Electrostatic potential is constant throughout the volume of the conductor. — Correct. Inside a conductor in electrostatic equilibrium \( \vec{E}=0 \), and \( E=-dV/dr=0 \) means the potential is the same at every point of the conductor.
(C) Electric field \( \vec{E} \) depends upon the distance between two thin infinite long uniformly charged plane sheets held parallel to each other. — Incorrect. The field of an infinite sheet is \( \sigma/2\varepsilon_0 \), independent of the distance, so the field between (or outside) two parallel sheets does not change with their separation.
(D) Electric field due to a uniformly charged spherical shell is zero at all points inside the shell. — Correct. By Gauss’s law a spherical Gaussian surface inside the shell encloses no charge, so the field is zero there.
(E) Electric field is in the direction in which the potential decreases steepest. — Correct. \( \vec{E}=-\nabla V \): the field points along the fastest fall of potential.
NCERT (2026-27):
Dielectrics and Polarisation – “… Thus in either case, whether polar or non-polar, a dielectric develops a net dipole moment in the presence of an external field.”
Electrostatics of Conductors – “… 4. Electrostatic potential is constant throughout the volume of the conductor and has the same value (as inside) on its surface”
Field Due to a Uniformly Charged Infinite Plane Sheet – “… Note that the above application of the Gauss’ law has brought out an additional fact: E is independent of x also.”
Field Due to a Uniformly Charged Thin Spherical Shell – “… that is, the field due to a uniformly charged thin shell is zero at all points inside the shell.”
Relation Between Field and Potential – “… (i) Electric field is in the direction in which the potential decreases steepest.”