A double boiler is used when a careful control of temperature is required in cooking. Water is boiled in an outside container to produce steam, and the steam condenses on the outside walls of an inner container in which cooking occurs. (A related laboratory device is called a steam bath.) 

(a) How is heat energy conveyed to the food to be cooked in a double boiler? 

(b) What is the maximum temperature that can be reached in the inside container?