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Which property is TRUE for electric field LINES?
ABegin and end on charges; never cross; density shows field strength
BThey can cross each other in regions of zero field
CThey form closed loops with no beginning or end
DThey are always radial, regardless of the charge distribution
Answer & Solution
Correct answer: A. Begin and end on charges; never cross; density shows field strength
1. NCERT §1.9 (Electric Field Lines) lists the properties.
2. Field lines BEGIN at positive charges and END at negative charges (or extend to infinity).
3. Field lines NEVER cross — if they did, the field at the crossing point would have TWO directions, contradicting the field being a well-defined vector at every point.
4. The DENSITY of lines is proportional to the field magnitude.
5. Option B is wrong — lines never cross, even at zero-field points. Option C describes magnetic field lines (closed loops), not electric ones from static charges. Option D is wrong — lines are radial only for spherically-symmetric distributions like point charges.
_Source: NCERT Class 12 Physics Part 1, Ch 1, §1.9 (Electric Field Lines), p. 23–24._
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