The complete set of important questions for CBSE class 7th science prepared by our subject experts contains all the explanations and step by step solutions for the chapters and topics in science. Download free pdf for practise.
Important questions based on NCERT syllabus for Chapter 4 - Heat:
Question-1: Differentiate between convection and conduction?
Solution: Conduction: Conduction is the process of transfer of heat from the hotter part to the colder part of an object without the movement of the particles. Also, in conduction, heat gets transferred between substances that are in direct contact with each other.
Convection: It is the process of transfer of heat by the movement of particles of a medium from one place to another. It takes place in liquid and gases.
Question-2: Which process is responsible for land and sea breeze? Explain the process and how it is different from radiation?
Solution: Convection is the process responsible for land and sea breeze. Convection is the process of transfer of heat from one place to another by the actual movement of the particles from one place to another. Particles carry heat from one place to another. In land and sea breeze, there is an actual movement of the particles from land to sea and from sea to land. Radiation is the process in which heat flows from one object to another object either through the medium or through vacuum, without heating up the space in between, is called radiation. In convection, medium is necessary for heat transfer from one end to another but in radiation, no medium is required for transferring of heat.
Question-3: What is meant by thermal equilibrium?
Solution: Heat flows from the body of higher temperature to the body of lower temperature, until or unless temperature of both the bodies becomes same. When the temperature of both the bodies becomes same then the bodies are said to be in thermal equilibrium. There will be no flow on heat from one body to another, if bodies are in thermal equilibrium.