Answer:
10.8 N
Step-by-step explanation:
The question requires the force between them, hence, we only need the magnitude of the force without considering what direction it's acting.
Parameters given:
Q1 = 15 * 10^(-6) C
Q2 = 10 * 10^(-6) C
The diagram explains better.
The electrostatic force BETWEEN Q1 and Q2 is:
F = (k * Q1 * Q2)/r²
Using Pythagoras theorem:
r² = 0.25² + 0.25² = 0.0625 + 0.0625
r² = 0.125
=> F = [9 * 10^9 * 15 * 10^(-6) * 10 * 10^(-6)]/0.125
F = 1.35/0.125
F = 10.8 N