High-powered LED floodlights used in sports stadiums generate significant thermal energy during operation. To prevent the LED chips from overheating and degrading, they are mounted onto a heavy metal cooling block with deep fins to transfer thermal energy away to the atmosphere.
A designer is testing three prototype cooling blocks of identical size and shape, but each has a different surface finish: matt black, shiny chrome, and white.
Explain why the cooling blocks are manufactured from metals such as copper or aluminium rather than plastics.
Explain which surface finish is most effective at transferring thermal energy to the surroundings by radiation.
The cooling block also transfers thermal energy to the air by convection.
Explain how a convection current is established in the air surrounding the hot cooling block.
Suggest one design modification to the physical structure of the cooling block that would maximise heat transfer by convection.
36 exam-style questions on Edexcel IGCSE Physics Energy transfers. Each one has a worked solution and a mark scheme showing where the marks go.