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In Coulomb's law, F = k q1 q2 / r^2, what is the value of Coulomb's constant k in SI units?
A8.99 x 10^9 N m^2/C^2
B6.67 x 10^-11 N m^2/C^2
C1.602 x 10^-19 N m^2/C^2
D8.85 x 10^-12 N m^2/C^2
Answer & Solution
Correct answer: A. 8.99 x 10^9 N m^2/C^2
1. Coulomb's law defines the constant of proportionality as k.
2. In SI units, k = 8.99 x 10^9 N m^2/C^2.
3. 6.67 x 10^-11 is the gravitational constant G, 1.602 x 10^-19 is the elementary charge e, and 8.85 x 10^-12 is the permittivity of free space, so none of those are Coulomb's constant.
_Source: OpenStax Physics (CC BY 4.0), Ch 18 "Static Electricity", section 18.2 Coulomb's law_
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