aluminium

steel

brass

copper

high thickness of insulation

high vapour pressure

less thermal conductivity insulator

a vapour seal

electric heater

steam condenser

melting of ice

boiler.

it is impossible to transfer heat from low temperature source to t high temperature source

heat transfer by radiation requires no medium

all bodies above absolute zero emit radiation

heat transfer in most of the cases takes place by combination of conduction, convection and radiation

I

0.5

2

0.25