Question Detail
Question
Find the value of two equal charges that repel each other with a force of 0.5N when placed 50cm apart in vacuum (k = 9x109).
Correct Answer
Option D is the correct answer.
Detailed Explanation
q = sqrt(F r2/k) = sqrt[(0.5)(0.5)2/9x109] = sqrt[0.125/9x109] = sqrt(1.389x10-11) = 3.73x10-6 C = 3.73 uC. (Note: this differs from Q8 because the force here is 0.5N, not 0.1N; the source's listed options appear to have been carried over incorrectly from Q8 - the correctly worked value is 3.73 uC.)
Hint
q = sqrt(F r2/k) = sqrt[(0.5)(0.5)2/9x109] = sqrt[0.125/9x109] = sqrt(1.389x10-11) = 3.73x10-6 C = 3.73 uC.