An uncharged solid metallic sphere with two cavities is placed with c…

An uncharged solid metallic sphere with two cavities is placed with centre of sphere at origin. Cavities have centres $C_1\left(0, \frac{3 R}{4}, 0\right)$ and $C_2\left(0, \frac{-3 R}{4}, 0\right)$ with same point charge Q placed at centres of cavities. Intensity of the field at point $P\left(\frac{3 R}{2}, 0,0\right)$ is