Physics

Physics

Problem

Four isolated pairs of point charges are arranged as follows (all charges are multiples of qq and all separations are multiples of dd): P. +q+q and +4q+4q at separation 2d2d Q. −2q-2q and +3q+3q at separation dd R. +5q+5q and −q-q at separation 3d3d S. +2q+2q and +2q+2q at separation 2 d\sqrt{2}\,d Ignoring signs when comparing magnitudes, choose the correct ascending order of the magnitudes of electrostatic force among these four cases. a) P < R < S < Q b) R < Q < P < S c) R < P < S < Q d) P < S < R < Q
Intuitive explanation

The electrostatic force between two point charges depends on both the product of their magnitudes and the square of their separation distance, following Coulomb's law F=k∣q1q2∣r2F = k\frac{|q_1 q_2|}{r^2}. To rank these forces, you need to calculate the numerator (product of charge magnitudes) and denominator (separation squared) for each pair, then compare the resulting ratios. The key is being systematic: compute ∣q1q2∣|q_1 q_2| and r2r^2 separately for each case, then divide to find which pairs produce the strongest and weakest interactions.

Intuitive explanation

The electrostatic force between two point charges depends on both the product of their magnitudes and the square of their separation distance, following Coulomb's law F=k∣q1q2∣r2F = k\frac{|q_1 q_2|}{r^2}. To rank these forces, you need to calculate the numerator (product of charge magnitudes) and denominator (separation squared) for each pair, then compare the resulting ratios. The key is being systematic: compute ∣q1q2∣|q_1 q_2| and r2r^2 separately for each case, then divide to find which pairs produce the strongest and weakest interactions.

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