Question

explain the role of glass top slab in a box type solar cooker

Answer 1

When sunlight falls over the solar cooker top, the sun rays pass through the glass sheet cover and get absorbed inside the cooker box.
This glass sheet covers does not allow the solar energy to flow out in the form of radiant heat.Thus it traps more and more heat rays of the sun thereby producing green house effect.That is why glass lid is used in the solar cooker.

Answer 2

Answer:

The box is covered with glass sheet this reduce heat loss by radiation and traps heat, which increase the temperature inside the box. The covered box is made airtight to reduce heat loss by convection.