Heat Transfer in Nature – Very Short Answer Type Questions
Class 7
Science
Chapter 7
Heat Transfer in Nature — 50 Very Short Answer Questions (NCERT-aligned)
These very short questions with answers follow the NCERT syllabus and are ideal for CBSE Class 7 board exam revision.
Scope: Quick revision questions covering conduction, convection and radiation and their roles in natural phenomena like the water cycle and groundwater movement. Keep answers short and precise for exam practice.
1. What is heat?
Heat is a form of energy that flows from a hotter body to a colder body.
2. What is conduction?
Conduction is heat transfer through direct contact between particles in a solid or between touching objects.
3. What is convection?
Convection is heat transfer by the movement of fluids (liquids or gases) due to density differences.
4. What is radiation?
Radiation is heat transfer through electromagnetic waves and does not require a medium.
5. Which mode of heat transfer works in vacuum?
Radiation works in vacuum.
6. Name a good conductor of heat.
Metals like copper and iron are good conductors of heat.
7. Name a good insulator.
Materials like wood, rubber, and plastic are good insulators.
8. Give one example of conduction in daily life.
A metal spoon becoming hot when its other end is placed in hot water.
9. Give one example of convection in nature.
Warm air rising from heated land forming sea breezes is an example of convection.
10. Give one example of radiation.
The Sun warming the Earth's surface is an example of radiation.
11. Why do metals feel colder than wood at room temperature?
Metals conduct heat away from your hand faster than wood, so they feel colder.
12. What causes convection currents?
Convection currents are caused by differences in fluid density due to temperature differences.
13. How does radiation depend on surface color?
Dark surfaces absorb radiation better and heat more than light or shiny surfaces.
14. Does conduction occur in gases?
Conduction occurs in gases but is much slower because particles are far apart.
15. What role does radiation play in the water cycle?
Solar radiation provides the energy for evaporation, starting the water cycle.
16. How does groundwater temperature get affected?
Groundwater temperature is influenced by conduction and slow movement of heat through soil and rocks.
17. What is thermal equilibrium?
Thermal equilibrium is when two objects in contact reach the same temperature and no net heat flows between them.
18. Why is space suit insulation important?
Space suit insulation protects astronauts by reducing heat loss/gain via conduction and radiation in space.
19. Define emissivity (simple).
Emissivity is how well a surface emits thermal radiation; higher emissivity means better emission.
20. Why do deserts have large day-night temperature differences?
Low moisture and sparse vegetation cause rapid heating by radiation during day and rapid cooling at night.
21. How does sea breeze form?
Sea breeze forms when land heats faster than sea; warm air over land rises and cool air from sea moves in.
22. How does land breeze form?
At night land cools faster than sea; air over sea is warmer and rises, causing cool air from land to flow towards sea.
23. What is conduction in terms of particles?
In conduction, vibrating particles transfer kinetic energy to neighbouring particles through collisions.
24. Give a kitchen example showing radiation.
Feeling heat from a hot oven or grill without touching it is due to radiation.
25. Why are rooftops painted white in hot regions?
White paint reflects more solar radiation, keeping roofs and buildings cooler.
26. What is natural convection?
Natural convection occurs due to natural temperature differences causing fluid motion, without external forces.
27. What is forced convection?
Forced convection involves external means (like fans or pumps) to move fluid and transfer heat.
28. How does insulation reduce heat transfer?
Insulation reduces heat transfer by providing materials with low thermal conductivity and trapping air pockets.
29. Why does a black car heat more in sun than a white car?
A black car absorbs more solar radiation, heating its surface more than a white car.
30. Name one factor that affects rate of conduction.
Thermal conductivity of the material affects the rate of conduction.
31. How does crowding of particles affect conduction?
Closer packed particles (as in solids) transfer heat more efficiently by conduction.
32. What happens to radiation from the Sun when it reaches Earth?
Some radiation is absorbed by land and water, some reflected back, and some heats the atmosphere.
33. Give an example of convection in oceans.
Warm surface water rising and cold deep water sinking create ocean convection currents.
34. How does vegetation affect ground temperature?
Vegetation shades the ground and reduces heating by radiation, keeping soil cooler.
35. Why are thermos flasks lined with reflective surfaces?
Reflective surfaces reduce heat loss by radiation, helping keep contents hot or cold longer.
36. What is latent heat (simple)?
Latent heat is the energy absorbed or released during a change of state, like evaporation, without temperature change.
37. How does evaporation cool a surface?
Evaporation absorbs latent heat from the surface, producing a cooling effect.
38. Does radiation depend on medium?
No, radiation does not depend on any medium and can travel through vacuum.
39. What is conduction used for in cooking?
Conduction transfers heat from a hot pan to the food being cooked.
40. How does colour of clothes affect heating?
Darker clothes absorb more radiation and heat the wearer more than lighter clothes.
41. What causes sea surface temperatures to change?
Solar radiation and ocean currents (convection) change sea surface temperatures.
42. How do buildings stay warm in winter (simple)?
Insulation, reduced radiation loss (double glazing) and heating systems keep buildings warm.
43. What is a conductor in everyday electricity/heat context?
A conductor is a material that allows easy transfer of heat (or electricity) like metals.
44. Why do lakes freeze from the top?
Water is densest at 4°C; colder water stays on top and freezes first, insulating lower layers.
45. How do winds help in heat transfer?
Winds move warm or cool air masses, aiding convective heat transfer over regions.
46. How does fog form (brief)?
Fog forms when moist air cools and water vapour condenses into tiny droplets near the ground.
47. Why are summers hotter near the equator?
The equator receives more direct solar radiation, so it is generally hotter year-round.
48. How can you reduce heat loss from a house?
Use insulation, seal gaps, and install reflective roofs or curtains to reduce heat loss.
49. What simple observation shows convection?
Watching hot water rise as steam and cold water sink in a pot shows convection currents.
50. In one line — why study heat transfer?
Studying heat transfer explains many natural processes and helps in solving real-life problems of heating and cooling.
Note: Answers are intentionally concise for quick revision and follow the NCERT syllabus for CBSE Class 7.