The electric field lines start from positive charges and end at negative charges. If there is a single charge, they __________.
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → may start or end at infinity
Electric field lines always start on positive charges and end on negative charges. With only one charge present, the other end of every line has to be at infinity.
For a single positive charge the lines start on the charge and go out to infinity.
For a single negative charge the lines come in from infinity and end on the charge.
So, depending on the sign of the charge, the lines may start or end at infinity.
Why the other options are incorrect
Option (1) must always start from the charge — Incorrect. This holds only for a positive charge; for a negative charge the lines end on the charge.
Option (2) must always start from infinity — Incorrect. This holds only for a negative charge; the lines of a positive charge start on the charge.
Option (4) may form closed loops — Incorrect. Electrostatic field lines never form closed loops, because the electrostatic field is conservative. Closed loops are a property of magnetic field lines.
NCERT (2026-27):
Electric Field Lines – “… The field lines follow some important general properties:
(i) Field lines start from positive charges and end at negative charges. If there is a single charge, they may start or end at infinity. …
(iv) Electrostatic field lines do not form any closed loops. This follows from the conservative nature of electric field (Chapter 2).”