Physics Allen Book Class 7 Contents 1. Heat 2. Motion & Time 3.Electric Current & Its Effect 4. light 1. Heat Heat:- Heat is the form of energy which flows between two objects or systems as a result of temparature difference between them. Heat is also called thermal energy . Units Of Heat:- It's S.I. unit is Joule (J). Other commonly used unit is Calorie (cal) Calorie is the amount of heat required to raise the temparature of 1 gram of water by 1 Degree Celcius