$2.$ The bond between two plates, $2\mathrm{.}5$ cm and $15$ cm thick, heat is uniformly applied through the thinner plate by a radiant heat source. The bonding epoxy must be held at $320$ K for a short time. When the heat source is adjusted to have a steady value of $\backslash (43\mathrm{.}5\backslash$mathrm$\{$~kW$\}/\backslash$mathrm$\{$m$\}^\{2\}\backslash ),$ a thermocouple installed on the side of the thinner plate next to source indicates a temperature of $345$ K $.$ Calculate the temperature gradient for heat conduction through thinner plate and thermal conductivity of its material.