Home › NEET UG › Physics › Electric Charges and Fields › Two point charges repel each other with force $F…
Two point charges repel each other with force $F$. If the distance between them is doubled while both charges stay unchanged, the new force becomes
A$F/2$
B$F/4$
C$2F$
D$4F$
Answer & Solution
Correct answer: B. $F/4$
1. Coulomb's law: $F = k\frac{q_1 q_2}{r^2}$ — force is inverse-square in distance.
2. New distance $r' = 2r$, so $r'^2 = 4r^2$.
3. New force $F' = k\frac{q_1 q_2}{4r^2} = F/4$.
4. Option A treats the law as inverse-linear; options C and D have the force growing with distance, which contradicts the inverse-square law.
_Source: NCERT Class 12 Physics Ch 1 "Electric Charges and Fields", §1.6 Coulomb's Law_
Related questions
A charged comb picks up small pieces of paper that carry no net charge, because the paper Compared with the tiny nucleus, the electrons around it form a cloud that is:Benjamin Franklin explained early observations by supposing that one type of charge stayedA test charge or a source charge moves, and as a result the force between them:If the two ends of a dipole can be pulled apart, induction can create charged objects withPlaced in a uniform field, such a dipole experiences a turning effect that changes its angTwo equal and opposite charges separated by a small distance form a dipole, characterised Where those lines are packed more densely, the field is: