If the distance between two charges is halved and magnitude of charges are also doubled, then the force between these charges becomes:
Correct answer: D. Sixteen times
- A. Two times
- B. Four times
- C. Eight times
- D. Sixteen times
Explanation
Doubling both charges multiplies the numerator of Coulomb's law by four, and halving the separation divides the denominator by four since the distance is squared, so the two effects combine to give sixteen times the original force. Handling the two changes separately and then multiplying is the safe method. Forgetting that the distance is squared gives the eight times answer.
This question appeared on the UHS MDCAT 2025 paper, which you can sit online with every answer explained.
Report an error
The more specific you are, the faster it gets fixed. A source beats an opinion.
Prefer email? support@testustad.com
About Coulomb's Law
Coulomb's law gives the electrostatic force between two point charges in terms of their magnitudes, separation and the medium between them. Questions involve attraction and repulsion, the inverse square relationship, superposition of forces and vector direction, which must not be confused with the electric field produced by a charge.
Practise Electrostatics
831 free Electrostatics MCQs from Physics, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Discussion
Stuck on an option, or know a faster way to get there? Ask or explain it here.
No comments yet. Be the first to explain this one.
Exams that ask Physics questions like this
Physics is on 16 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
More Coulomb's Law questions
If a plastic sheet of relative permittivity 2.5 is inserted between two point charges placed in vacuum, then the electrostatic force between them
The force between two charges placed in a medium of relative permittivity 4, compared with the force in a vacuum, is
If the distance between two point charges is halved, the electrostatic force between them becomes
When two charges are placed in water then the Coulomb force between them reduces to _____________?
Two identical metal balls with charges + 2Q and - Q are separated by some distance, and exert a force F on each other. They are joined by a conducting wire, which is then removed. The force between them will now be_________?
Two charges q1 and q2 are placed in vacuum at a distance d and force between them is F. If a medium of relative permittivity 4 is introduced between them then new force will be: