A student constructed a model of box-type solar cooker. Instead of using glass sheet he used a transparent plastic sheet to cover the open face of the box. He found that this cooker does not function well. What could be the possible drawbacks in his model? Explain the advantage of painting black the inner and outer surfaces of the cooker and that of cooking vessels.
The solar cooker made by the student does not function well because he used transparent plastic sheet to cover the open face of the box. The transparent plastic sheet is not much effective in trapping the sunlight to heat up the cooker. Instead of plastic sheet, he should have used a transparent glass sheet to cover the open face of the box.
This is because glass sheet can trap the heat rays of sun very effectively by producing the greenhouse effect.
Black colour is very good absorber of heat. So, painting the inner and outer surface of the cooker along with the cooking vessels with black will enhance the absorption of the heat rays of the sun.