Transfer of thermal energy

Which process of thermal energy transfer is due to change in density?

• Conduction

• convection

• radiation

• evaporation

which surface is the best emitter of thermal energy

• shiny black

• shiny silver

• dull black

• dull silver

The diagrams show part of a water-heating system which is working by convection.

Which diagram shows the most likely flow of water in the system?

• A

• B

• C

• D

How does thermal energy (heat energy) travel through the vacuum between the Earth and the Sun?

• by conduction

• by convection

• by radiation

• by evaporation

A person holds a glass beaker in one hand and fills it quickly with hot water. It takes several

seconds before his hand starts to feel the heat.

Why is there this delay?

• Glass is a poor conductor of heat.

• Glass is a good conductor of heat.

• Water is a poor conductor of heat.

• Water is a good conductor of heat.

An experiment is set up to find out which metal is the best conductor of heat. Balls are stuck with wax to rods made from different metals, as shown in diagram X.

The rods are heated at one end. Some of the balls fall off, leaving some as shown in diagram Y.

Which labelled metal is the best conductor of heat?

• A

• B

• C

• D