Answer:
6.45 a
Explanation:
Charge on O, q1 = 4q
Charge on A, q2 = - 3 q
OA = a
Let the net force is zero at point P, where AP = x , let a charge Q is placed at P.
The force on point P due to the charge q1 = The force on point P due to the
charge q2
By using Coulomb's law
[tex]\frac{Kq_{1}Q}{OP^{2}}=\frac{Kq_{2}Q}{AP^{2}}[/tex]
[tex]\frac {K4qQ}{(a+x)^{2}}= \frac {K3qQ}{x^{2}}[/tex]
[tex]\frac{a+x}{x}=\sqrt{\frac{4}{3}}[/tex]
[tex]\frac{a+x}{x}=1.155[/tex]
a + x = 1.155 x
0.155 x = a
x = 6.45 a
Thus, the force is zero at x = 6.45 a.