Consider the following statements:
(A) The net magnetic flux through any closed surface is zero.
(B) Isolated magnetic monopoles exist, just like isolated positive and negative charges.
(C) Electrostatic field lines begin on a positive charge and end on a negative charge or fade out at infinity.
(D) The reason why electric charge is quantised is well known.
Which of the above statements are incorrect?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → (B) and (D) only
Electric charges and magnetic poles behave very differently. Isolated positive and negative charges exist. Magnetic poles always come in pairs, so a magnet has no source or sink of field lines.
(A) The net magnetic flux through any closed surface is zero. — Correct statement. This is Gauss’s law for magnetism. As many field lines enter a closed surface as leave it.
(B) Isolated magnetic monopoles exist, just like isolated positive and negative charges. — Incorrect statement. Magnetic monopoles do not exist. Slicing a magnet in half only gives two smaller magnets.
(C) Electrostatic field lines begin on a positive charge and end on a negative charge or fade out at infinity. — Correct statement. This is how electrostatic field lines behave. Magnetic field lines, by contrast, form closed loops.
(D) The reason why electric charge is quantised is well known. — Incorrect statement. Nobody knows yet why charge is quantised. The reason why monopoles do not exist is also not known.
NCERT (2026-27):
Magnetism and Gauss’s Law – “Thus, Gauss’s law for magnetism is: The net magnetic flux through any closed surface is zero.”
Points to Ponder – “2. Magnetic monopoles do not exist. If you slice a magnet in half, you get two smaller magnets.”
Points to Ponder – “3. … In contrast, the electrostatic lines of force begin on a positive charge and terminate on the negative charge (or fade out at infinity).”
Points to Ponder – “… We do not know why magnetic monopoles do not exist or why electric charge is quantised.”