I saw that an ice block melts faster when it is placed in a microwave rather than when it is exposed to flame. Could it be because the flame creates a layer of water vapor between the flame and ice? If not, what is the real reason for this?
When you heat An ice cube over a flame then heat is absorbed due to conduction and heat flows one sidedly only however in a micro wave the electromagnetic radiations have a greater penetrating power and they start moving dipoles present in ice because of which there is an increase in their vibrational energy, now because of friction between layers heat is generated which melts the ice. These radiation have an advantage as they can cover a larger volume of ice as when you heat ice by conduction thus ice will melt faster in an oven than when you put it over flame.