Match List-I with List-II.
| List-I | List-II |
|---|---|
| (A) A system has charges \(+5\ \mu\mathrm{C}\) and \(-2\ \mu\mathrm{C}\). Its total charge is \(+3\ \mu\mathrm{C}\). | (I) Quantisation of charge |
| (B) When a glass rod is rubbed with silk, the silk gains as much negative charge as the rod gains positive charge. | (II) Additivity of charge |
| (C) No body can have a charge of \(2.4\times10^{-19}\ \mathrm{C}\). | (III) Invariance of charge |
| (D) The charge on a body has the same value in frames of reference moving relative to each other. | (IV) Conservation of charge |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → (A)-(II), (B)-(IV), (C)-(I), (D)-(III)
(A) A system has charges \( +5\ \mu\mathrm{C} \) and \( -2\ \mu\mathrm{C} \). Its total charge is \( +3\ \mu\mathrm{C} \). — This matches (II) Additivity of charge. Charges add like real numbers, with their signs, so \( +5-2=+3 \).
(B) When a glass rod is rubbed with silk, the silk gains as much negative charge as the rod gains positive charge. — This matches (IV) Conservation of charge. Rubbing only moves electrons from the rod to the silk. No charge is created, so what the silk gains the rod loses.
(C) No body can have a charge of \( 2.4\times10^{-19}\ \mathrm{C} \). — This matches (I) Quantisation of charge. This value is 1.5 times \( e \). The charge on a body must be a whole-number multiple of \( e \), so this value is not possible.
(D) The charge on a body has the same value in frames of reference moving relative to each other. — This matches (III) Invariance of charge. Observers moving relative to each other measure the same charge on the body.
NCERT (2026-27):
Additivity of charges – “… If a system contains n charges q1, q2, q3, …, qn, then the total charge of the system is q1 + q2 + q3 + … + qn .”
Charge is conserved – “… no new charges are either created or destroyed. … When we rub two bodies, what one body gains in charge the other body loses.”
Quantisation of charge – “… Thus the charge on any body is always an integral multiple of e and can be increased or decreased also in steps of e.”
Points to Ponder – “6. Charge is not only a scalar (or invariant) under rotation; it is also invariant for frames of reference in relative motion.”