Consider the following statements about electric field lines:
(A) The field lines of a single positive charge are radially inward.
(B) The tangent to a field line at any point gives the direction of the net field at that point.
(C) Field lines crowd together where the field is weak and are spaced apart where it is strong.
(D) A field line is a space curve, that is, a curve in three dimensions.
Which of the above statements are incorrect? Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → (A) and (C) only
Field lines are a picture of the electric field. Their direction shows the direction of the field, and how close they are shows how strong it is.
(A) The field lines of a single positive charge are radially inward. — False. Field lines start from a positive charge. So the lines of a single positive charge point radially outward. The lines of a single negative charge point radially inward.
(B) The tangent to a field line at any point gives the direction of the net field at that point. — True. A field line is drawn so that its tangent at each point is along the net field there. An arrow on the line picks one of the two directions.
(C) Field lines crowd together where the field is weak and are spaced apart where it is strong. — False. It is the other way round. The lines come close together where the field is strong, for example near a charge, and spread out where it is weak.
(D) A field line is a space curve, that is, a curve in three dimensions. — True. The field exists all around the charges, so its lines run in space. A figure on paper shows only the lines lying in one plane.
NCERT (2026-27):
Electric Field Lines – “… The field lines of a single positive charge are radially outward while those of a single negative charge are radially inward.”
Electric Field Lines – “… a curve drawn in such a way that the tangent to it at each point is in the direction of the net field at that point.”
Electric Field Lines – “… The field lines crowd where the field is strong and are spaced apart where it is weak.”
Electric Field Lines – “… A field line is a space curve, i.e., a curve in three dimensions.”