if 3e charge is at the origin and magnesium nucleus is 3 cm from the origin in the x-direction. what is the magnitude of the net force a boron nucleus would experience half way between magnesium nucleus and 3 e charge
q₁ = 3 e,
q₂ = 12e,
q₃ = 5e
The electric field at the midpoint is
E= kq₂/(x/2)²- kq₁/(x/2)²=
=k(12e-3e)/(x/2)² =k36e/x² (directed to the 3e charge)
F= q₃E=k36e•5e/x²=
=k•180e/x²,
where
k =9•10⁹ N•m²/C²,
e =1.6•10⁻¹⁹ C,
x is the distance between 3e and 12e