Transfer of heat

Written by Dr. Hamza Farooq (Physics)

Class 9 · Physics · 10 questions

Name: ____________________ Date: ____________

Heat travels through a solid mainly by:
- A Convection
- B Conduction
- C Radiation
- D Evaporation
Heat reaches the Earth from the Sun by:
- A Radiation
- B Reflection only
- C Convection
- D Conduction
Convection takes place in:
- A Fluids
- B Solids only
- C A vacuum
- D Metals only
Which of these is a good conductor of heat?
- A Air
- B Wood
- C Copper
- D Plastic
A vacuum flask keeps liquids hot mainly because it reduces:
- A Conduction, convection and radiation
- B Only radiation
- C Only conduction
- D Only the liquid's mass
Which colour of surface is the best absorber of heat radiation?
- A Dull black
- B Silver
- C Shiny yellow
- D White
Sea breeze is caused by:
- A Radiation only
- B Evaporation only
- C Conduction
- D Convection currents
The handle of a cooking pan is made of plastic because plastic is a:
- A Good conductor
- B Poor conductor of heat
- C Good radiator
- D Metal
Which surface is the poorest emitter of heat radiation?
- A Dull black
- B Rough brown
- C Dark grey
- D Shiny silver
Heat transfer by the movement of heated fluid is called:
- A Radiation
- B Reflection
- C Convection
- D Conduction

Answer key

1. B, 2. A, 3. A, 4. C, 5. A, 6. A, 7. D, 8. B, 9. D, 10. C

In solids heat is passed from particle to particle by conduction.
Radiation does not need a medium, so it can cross empty space.
Convection needs the bulk movement of a liquid or gas.
Metals such as copper conduct heat well. Wood, plastic and air are poor conductors.
The vacuum stops conduction and convection, and the shiny walls reduce radiation.
Dull black surfaces absorb and emit radiation best.
Warm air rises over the land and cooler air moves in from the sea.
It stops heat reaching the hand.
Shiny surfaces emit and absorb less radiation.
Convection transfers heat by bulk flow.