Key Points

Heat

Important Points

  • Heat and temperature are different quantities.
  • SI unit of temperature is Kelvin; commonly we use Celsius (°C).
  • Dark, dull surfaces absorb more heat; shiny surfaces reflect more.
  • We wear light-coloured, loose clothes in summer and dark, tight clothes in winter.

Remember This

  • Conduction → Solids
  • Convection → Liquids and gases
  • Radiation → Even vacuum

Exam Tips

  • Practise reading a thermometer diagram — the mercury level must be at eye level.
  • For 'why' questions, always mention the *direction* of heat flow.

Definitions

Heat
The energy transferred because of a temperature difference.
Temperature
A measure of how hot or cold a body is.
Conductor
A material that lets heat pass through easily (e.g. metals).
Insulator
A material that does not let heat pass easily (e.g. wood, plastic).