The diagram shows the gap between a hot surface and a cold surface. The gap can contain air (gas), iron (solid), a vacuum or water (liquid). cold gap
hot
Which material in the gap allows the quickest transfer of thermal energy between the surfaces by conduction?
air (gas)
iron (solid)
vacuum
water (liquid)
The diagram shows four rods. Each rod is made of a different metal.
Wax is used to attach small metal balls at the rod ends P, Q, R and S.
Each rod is the same size. They are heated uniformly by a Bunsen burner at point X.
As the rods warm up, the wax melts and the balls fall off.
Why does the ball on the silver rod fall first?
Silver is the best conductor of heat.
Silver is the worst conductor of heat.
Silver is the best radiator of heat.
Silver is the worst radiator of heat.
A sealed metal box contains a fixed mass of air. The sides of the box are insulated.
A scientist investigates the thermal conductivity of air. She measures how quickly thermal energy passes between the top and bottom of the box.
Which row gives the correct procedure and conclusion?
procedure
conclusion
heat bottom surface
air is a good thermal conductor
heat bottom surface
air is a poor thermal conductor
heat top surface
air is a good thermal conductor
heat top surface
air is a poor thermal conductor