A solid insulation sample has a dielectric constant ${}_r$ of $3$ and a loss factor $tan$ of $0\mathrm{.}1.$ The conducti vity of the material is ${4\mathrm{.}8}^{***{10}^{-11}}\frac{S}{c}m$ The sample is subjected to a dc field of $40k\frac{V}{c}m.$

The heat generated from the sample $($ mill Watt$/c{m}^3),$

a$.76\mathrm{.}8$

b$.19\mathrm{.}2$

c$.4\mathrm{.}8$

d$.10\mathrm{.}8$

e$.$ None

If the sample is subjected to ac field of the same rms value $(40\frac{k}{c}m),$ then the frequency of breakdown in Hz is$,$

a$.288$

b$.172\mathrm{.}8$

c$.108$

d$.216$

e$.$ None