Answer:
q₁ / q₂ = 4
Explanation:
In this exercise we must use Coulomb's law
F = k q₁q₂ / r²
For this case the electric force is
F = k q₁ Q / r₁²
indicate that another particle q₂ has the same force on Q, but for r₂ = r₁ /2
F = k q₂ Q / r₂²
we equate the two equations
q₁Q / r₁² = q₂ Q / r₂²
we substitute r₂
q₁Q / r₁² = q₂ Q / (r₁/2)²
q₁ = q₂ 4
the relationship between the two charges is
q₁ / q₂ = 4