Radiation Lesson

Multiple Choice

By which process is thermal energy transferred through a vacuum?

• conduction only

• convection only

• conduction and convection only

• radiation only

Multiple Choice

A slice of bread is placed under a red-hot electric grill to make toast. What is/are the main process/processes by which the energy reach the bread?

• By conduction only.

• By conduction and convection

• By convection and radiation

• By radiation only

Multiple Choice

We feel the intense heat from the Sun when we stand in the open during noon time. How is heat transferred from the Sun to the Earth?

• By radiation only.

• By conduction and radiation only.

• By convection and radiation only.

• By conduction, convection and radiation.

Multiple Choice

A piece of aluminium foil is used to wrap around food to be cooked in an oven. The foil has a shiny side and a dull side. Which side should be on the outside and why?

• The dull side should be on the outside because it absorbs heat by radiation faster.

• The shiny side should be on the outside because it is a better conductor of heat.

• The dull side should be on the outside because it encourages convection current to be set up.

• The shiny side should be on the outside because it is a better absorber of heat by radiation.

Multiple Choice

A few soccer boys were trapped in a cave in Thailand in 2018. One of the things that rescuers did was to wrap a thin plastic blanket, with a shiny metallic surface, around the boys. What type of thermal energy transfer (heat loss) is the shiny surface intended to reduce?

• conduction

• convection

• radiation

• conduction and convection

Multiple Choice

A chair is several feet from a fireplace. The side of the chair facing the fireplace gets warm due to

• conduction
• convection
• radiation

Multiple Choice

When you use a microwave, what is the main way that heat is transferred?

• Convection
• Conduction
• Radiation
• insulation.

Multiple Choice

Sunbathing is an example of...

• conduction

• convection

• radiation

Multiple Choice

By which process is thermal energy transferred through a vacuum?

• conduction only

• convection only

• conduction and convection only

• radiation only

Multiple Select

Which type of surfaces are better absorbers or emitters of infra-red radiation?

• black

• smooth

• rough / dull

• white

• shiny

If you want to walk around on a hot sunny day (like visiting the zoo or the beach), what colour of clothes would you wear? Why?

Radiation

White or light-coloured clothings.

​

They are poor absorbers of infra-red radiation, so they will not absorb heat as much. ​

How radiation works

Open Ended

State the three factors that affect rate of heat transfer by radiation.