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Introduction to Heat and its effect Video Lecture | Science Class 7 (Old NCERT)

FAQs on Introduction to Heat and its effect Video Lecture - Science Class 7 (Old NCERT)

1. What is heat and how does it affect objects?
Ans. Heat is a form of energy that is transferred from one object to another due to a difference in temperature. When an object absorbs heat, its particles gain energy and start moving faster, causing an increase in temperature. This can lead to various effects such as expansion, melting, evaporation, or chemical reactions, depending on the nature of the object.
2. How is heat transferred between objects?
Ans. Heat can be transferred through three main processes: conduction, convection, and radiation. Conduction occurs when heat is transferred through direct contact between objects. Convection involves the movement of heat through the circulation of fluids, such as air or water. Radiation is the transfer of heat through electromagnetic waves, which can travel through a vacuum, unlike conduction and convection.
3. Why do different materials have different responses to heat?
Ans. Different materials have different responses to heat due to their molecular structure and composition. Materials with closely packed particles, such as metals, conduct heat well because the particles can easily transfer energy to neighboring particles. On the other hand, materials with loosely packed particles, like gases or insulators, do not conduct heat efficiently and may have a slower response to changes in temperature.
4. How does heat affect the expansion of objects?
Ans. Heat causes objects to expand because it increases the kinetic energy of the particles within the object. As the particles gain energy, they move more vigorously and occupy a larger space, resulting in expansion. This phenomenon is commonly observed in substances like solids, liquids, and gases, where expansion can lead to changes in dimensions or volume.
5. Can heat cause changes in the state of matter?
Ans. Yes, heat can cause changes in the state of matter. When a substance is heated, its particles gain energy and move more rapidly. If the substance reaches a certain temperature, it can undergo a phase change. For example, a solid can melt into a liquid, or a liquid can evaporate into a gas, depending on the specific conditions. These changes in state are reversible and can also occur in the opposite direction when heat is removed.
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