A solid insulating sphere of radius $10\ \text{cm}$, centre $O$, carries a uniform charge density of $+3.0\ \mu\text{C/m}^3$. A spherical cavity of radius $4.0\ \text{cm}$ has been cut out of it. The centre $O'$ of the cavity is $5.0\ \text{cm}$ from $O$, so $O$ itself lies in the charged material, as in the figure. The cavity is empty, and nothing else is nearby. The material itself does not change the field, so treat the charge as if it sat in empty space. Take $\varepsilon_0 = 8.85 \times 10^{-12}\ \text{C}^2\,\text{N}^{-1}\,\text{m}^{-2}$. Which of the following statements are correct?

Fig. 1: A cross-section of a uniformly charged sphere of radius 10 cm with centre O. A spherical cavity of radius 4.0 cm is cut out of it; its centre O prime is 5.0 cm to the right of O, so O lies in the charged material. The sphere is shaded and the cavity is white.