Question

A student constructed a model of a box type solar cooker. Instead of using a 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.

Answer 1

Solar cooker will work properly when solar light of particular wavelength can pass through the open side and provide better heating capabilities. In the section below we will be discussing the type of wavelength and type of sheet to be used to cover the open part of the solar cooker.

Complete solution:
To understand the solution for our problem first we need to know that, solar cookers can’t cook food from sunlight itself nor is the outside temperature which can affect the cooking process but the sun rays that will be converted into heat energy that cook the food. The conversion can be maximized by using materials that can conduct and retain heat in the system.

Now, solar cookers works best on the longer wavelengths due to some heating capabilities and from glass sheet they can easily pass through but in the case of plastic sheet it will reflect longer wavelengths eventually and solar cooker will not work properly or we can say that glass sheet is used to retain the heat contained in the box, if plastic sheet is used heat would be lost at very much extent, so these points are some drawback of his model.

Now, solar cookers work on solar energy which is very low so as to maximize the usage of energy cookers and vessels are painted black, because black absorbs maximum heat and makes sure that maximum heat can be absorbed by the cooker.

Note:
Solar cookers are very useful as they do not require any fuel or anything which saves cost and saves the environment by not producing any type of pollution, but in cloudy weather they are less useful and take longer time to cook food than a stove or oven.