From a conducting sphere of radius R a cavity of radius R/2 is cut ou…

$V=\frac{q}{2 \pi \varepsilon_0 d}, E=\frac{q}{2 \pi \varepsilon_0 d^2}$

$V=\frac{q}{4 \pi \varepsilon_0 d}, E=\frac{q}{2 \pi \varepsilon_0 d^2}$

$V=\frac{q}{4 \pi \varepsilon_0 d}, E=\frac{q}{4 \pi \varepsilon_0 d^2}$

$V=\frac{q}{2 \pi \varepsilon_0 d}, E=\frac{q}{4 \pi \varepsilon_0 d^2}$