To identify the set with the stronger interaction between two objects that each carry a charge of -1 coulomb or +1 coulomb, the student can ask the following question:
"What is the distance between the charged objects in each set?"
This question is crucial because the electric force between two charged objects is described by Coulomb's law, which states that the force \( F \) between two point charges is proportional to the product of the magnitudes of the charges and inversely proportional to the square of the distance between them:
\[ F = k \frac{{|q_1 \cdot q_2|}}{{r^2}} \]
where:
- \( F \) is the force between the charges,
- \( k \) is Coulomb's constant,
- \( q_1 \) and \( q_2 \) are the charges (either -1 or +1 coulomb in this case),
- \( r \) is the distance between the charges.
Thus, knowing both the magnitude of the charges (which are equal for both sets) and the distance between the charges will allow the student to determine which set has the stronger interaction. The set of charges that are closer together will exert a stronger force on each other, as the force decreases with the square of the distance.