Figure shows, in cross section, two solid spheres with uniformly distributed charge throughout t...

Figure shows, in cross section, two solid spheres with uniformly distributed charge throughout their volumes. Each has radius \( R \). Point \( P \) lies on a line connecting the centers of the spheres, at radial distance \( R / 2 \) from the center of sphere 1. If the net electric field at point \( P \) is zero, and \( Q_{1} \) is \( 64 \mu \mathrm{C} \) and \( Q_{2}=8 x \mu \mathrm{C} \), what is the value of \( x \).