Choose the correct statements from the following:
A. The total charge in any isolated system remains constant.
B. When some charge is transferred to a conductor, it stays at the same place without getting distributed over the entire surface.
C. One Coulomb of negative charge is the total charge of \( 6.25\times10^{18} \) electrons.
D. Electric field is a scalar field.
E. Permanent dipole means that the dipole moment \( \vec{p} \) exists irrespective of external electric field \( \vec{E} \)
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → A, C and E only
(A) The total charge in any isolated system remains constant. — Correct. This is the conservation of charge: charge can be transferred but neither created nor destroyed.
(B) When some charge is transferred to a conductor, it stays at the same place without getting distributed over the entire surface. — Incorrect. Charge given to a conductor spreads over its surface, because like charges repel each other and the charge is free to move.
(C) One Coulomb of negative charge is the total charge of \( 6.25\times10^{18} \) electrons. — Correct. The charge of one electron is \( 1.6\times10^{-19}\,\mathrm{C} \), so
\( \displaystyle n = \frac{1\,\mathrm{C}}{1.6\times10^{-19}\,\mathrm{C}} = 6.25\times10^{18} \)
(D) Electric field is a scalar field. — Incorrect. The electric field has a magnitude and a direction at every point, so it is a vector field.
(E) Permanent dipole means that the dipole moment \( \vec{p} \) exists irrespective of external electric field \( \vec{E} \) — Correct. A molecule with a permanent dipole, such as HCl, has a dipole moment even with no field; in non-polar molecules a dipole moment appears only when a field induces it.
NCERT (2026-27):
Charge is Conserved – “… Within an isolated system consisting of many charged bodies, due to interactions among the bodies, charges may get redistributed but it is found that the total charge of the isolated system is always conserved.”
Conductors and Insulators – “… When some charge is transferred to a conductor, it readily gets distributed over the entire surface of the conductor.”
Quantisation of Charge – “… Thus, there are about 6 × 1018 electrons in a charge of –1C.”
Dipole in a Uniform External Field – “… (By permanent dipole, we mean that p exists irrespective of E; it has not been induced by E.)”