Answer:
Charge on least sphere, q = 570 nC
Step-by-step explanation:
It is given that,
Two small plastic spheres are given positive electrical charges. The distance between the spheres, r = 30 cm = 0.3 m
The repulsive force acting on the spheres, F = 0.13 N
If one sphere has four times the charge of the other.
Let charge on other sphere is, q₁ = q. So, the charge on first sphere is, q₂ = 4 q. The electrostatic force is given by :




q = 570 nC
So, the charge on the least sphere is 570 nC. Hence, this is the required solution.