Question: An electric heater with the total surface area of 0.25m^2 and emissivity of 0.75 is in a room where the air has a temp of 20 degrees Celsius and the walls are at 10 degrees Celsius. When the heater consumes 500W of electric power, its surface has a steady temperature of 120 degrees Celsius.
Part A- Determine the temperature of the heater surface when it consumes 700W of power.
I need help to calculate the temperature of the heater surface.