Consider a thin $24$ cm$-$long and $20cm-$wide horizontal plate snspended in air at $20C.$ The plate

is equipped with electric resistance heating wire. Now the heater is traned on and the plate

temperature rises and reaches $30C$ at steady state operating conditions. The plate has an

emissivity of $=0\mathrm{.}80$ and $=5\mathrm{.}67{10}^{-8}.$ Calculate the total rate of heat transfer that has been

generated in the element.