Match List-I with List-II.
| List-I (Law) | List-II (What it tells) |
|---|---|
| (A) Gauss’s law for electricity | (I) The net magnetic flux through a closed surface is zero. |
| (B) Gauss’s law for magnetism | (II) A changing electric flux produces a magnetic field. |
| (C) Faraday’s law | (III) The electric flux through a closed surface depends on the charge inside it. |
| (D) Ampere-Maxwell law | (IV) A changing magnetic flux induces an emf. |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → (A)-(III), (B)-(I), (C)-(IV), (D)-(II)
(A) Gauss’s law for electricity — This matches (III). The flux of \( \vec E \) over a closed surface equals \( Q/\varepsilon_0 \), where \( Q \) is the charge inside it.
(B) Gauss’s law for magnetism — This matches (I). The flux of \( \vec B \) over any closed surface is zero, because no isolated magnetic poles (monopoles) are known.
(C) Faraday’s law — This matches (IV). The induced emf equals the rate of change of magnetic flux.
(D) Ampere-Maxwell law — This matches (II). The magnetic field around a loop comes from the conduction current and also from the displacement current \( \varepsilon_0\,d\Phi_E/dt \). The displacement current is due to a changing electric flux.
NCERT (2026-27):
Maxwell’s equations
\( \oint\vec E\cdot d\vec A=Q/\varepsilon_0 \)\( \qquad \text{(Gauss's Law for electricity)} \)
\( \oint\vec B\cdot d\vec A=0 \)\( \qquad \text{(Gauss's Law for magnetism)} \)
Displacement Current – “… Faraday’s law of induction states that there is an induced emf equal to the rate of change of magnetic flux. …”
Summary – “… This displacement current is due to time-varying electric field and is given by id = ε0 (dΦE/dt) and acts as a source of magnetic field in exactly the same way as conduction current.”