A flat plate of polished copper of surface emissivity 0.1 is 0.1 m long and 0.1 m wide. The plate is placed vertically, with one side heated to a surface temperature of 500 K, and the other side remaining insulated. The heated side is exposed to quiescent air at 300 K and the surroundings are also at 300 K. Assume that air can be taken as an ideal gas. Estimate the heat rate from the flat plate.

The heat rate is  

Explanation:

From the question we are told that

  The surface emissivity is  

   The length is  

    The width is  

     The surface temperature of one side is  

     The temperature of the quiescent air

      The temperature of the surrounding is  

The heat rate from the flat plate is mathematically represented as

Where is the quiescent air Stefan-Boltzmann constant  and it value is

     A is the area which is mathematically evaluated  as

substituting values

substituting values

i think the answer is a and b

i wish you luck