Back to Coulomb's Law — Problem 4 · Task Set 4

Exercises: Coulomb's Law

Work through each section in order. Use $k = 9 \times 10^9$ N·m²/C² throughout. Show your work on all calculation problems.

Grade 11·20 problems·~35 min·OpenStax Physics (High School)·section·sec-18-2

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Fluency Practice

Use $k = 9 \times 10^9$ N·m²/C². Show your work and state the direction of each force.

The electric force between two charges separated by distance $r$ is $F$ . If the distance is doubled to $2r$ (charges unchanged), what is the new force?

$\frac{F}{2}$ — distance doubled, force halved

$\frac{F}{4}$ — distance doubled, force reduced by factor of 4

$2F$ — force doubles when distance doubles

$4F$ — force quadruples when distance doubles