Take a glass tube and drop an ice cube wrapped in wire gauge in it
Now fill 3/4th of this tube with water and place it alwe the burner as shown in the figure .
You can observe that the water boils at the edge and the ice present in the bottom of the tube has not melted indicating that heat has not reached the bottom where the ice cube is present This proves that water is a bad conductor of heat. It is easy to heat water easily or quickly while cooking. This is because, while cooking the vessel or pan is usually covered with a lid.
This leads to three things:
(i) Radiation from the hot water in reflected back into the pan rather than being emitted
(ii) Free convection is effectively eliminated, and
(iii) Evaporative cooling is also eliminated.
This in turn allows the water to be heated more easily .
