Which of the following statements are correct?
A. The algebraic sum of potential drops around any closed loop is zero.
B. Metals have high resistivity
C. The potentiometer is a device in which a condition of no current flow applies.
D. Kirchhoff's junction rule is based on conservation of charge
E. Bending the wire changes the validity of Kirchhoff's junction rule.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → A, C and D only
(A) The algebraic sum of potential drops around any closed loop is zero. — Correct. This is Kirchhoff’s loop rule, which expresses conservation of energy: a charge taken round a closed loop returns to its starting potential.
(B) Metals have high resistivity — Incorrect. Metals are good conductors with low resistivity, of the order of \( 10^{-8}\) to \(10^{-6}\,\Omega\,\mathrm{m} \).
(C) The potentiometer is a device in which a condition of no current flow applies. — Correct. At the balance (null) point no current flows through the galvanometer, so the cell whose emf is measured is not drawing any current.
(D) Kirchhoff’s junction rule is based on conservation of charge — Correct. In steady flow charge cannot pile up at a junction, so the current entering equals the current leaving.
(E) Bending the wire changes the validity of Kirchhoff’s junction rule. — Incorrect. The junction rule depends only on charge being conserved, not on the shape of the wires, so it holds however they are bent.
Note: Statements (A), (B), (D) and (E) of this question are from the latest textbook (2026-27). Statement (C), on the potentiometer, is printed only in the pre-rationalised textbook (2022-23). It was removed from the latest book, and it also appears to be out of the CUET 2026 syllabus.
NCERT (2026-27):
Summary – “… Metals have low resistivity, in the range of 10–8 Ω m to 10–6 Ω m.”
Summary – “… (b) Loop Rule: The algebraic sum of changes in potential around any closed loop must be zero.”
Points to Ponder – “… 6. Kirchhoff’s junction rule is based on conservation of charge and the outgoing currents add up and are equal to incoming current at a junction. Bending or reorienting the wire does not change the validity of Kirchhoff’s junction rule.”
NCERT (Pre-rationalised edition, 2022-23):
Summary – “… 15. The potentiometer is a device to compare potential differences. Since the method involves a condition of no current flow, the device can be used to measure potential difference; internal resistance of a cell and compare emf’s of two sources.”