Here's my Sunday lunch cooking in Kershopehead Bothy - vegetarian's nightmare I'm afraid. How does the thermal energy get from the stove to the food? First of all the combustion reaction between the gas and the air releases energy in the form of heat. If the flame is touching the pan then there will be direct conduction. If the flame is a little below the pan, the thermal energy will heat the air. The air will expand and float up to hit the bottom of the pan. Then there will be conduction from the air to the pan. The thermal energy will go through the pan itself by conduction. Conduction is much better in the metal because there are free electrons which can go ahead and hit ions further ahead in the atomic structure (the lattice). The bacon and sausages were touching the metal so thermal energy conducts through into the meat. A lot of energy is wasted heating the air above the pan. It expands, becomes less dense and floats away by convection. The efficiency is probably low because so much is wasted but I didn't mind because the useful energy cooked my lunch.
