Heat Transfer

Science — Second Preparatory

Heat Transfer

Applications and examples

Comparison aspect	Main idea	Keywords
Experiment 1: conduction in metal.	Fix several pins to a copper rod with wax then heat one end with a candle flame. The pins fall one after another starting with the pin nearest the flame. This shows that heat travelled along the metal	severalpinscopperthen
Experiment 2: convection in water.	Place a crystal of potassium permanganate at the bottom of a beaker of warm water (carefully) and watch the purple colour rise and spread. The upward and downward movement of the water shows the convection currents	Placecrystalpotassiumpermanganate
Experiment 3: radiation.	Place two identical thermometers in front of a lamp. Paint the bulb of one of them black and leave the other shiny. The black thermometer records a larger rise in temperature because it absorbs more radiation	Placeidenticalthermometersfront

Example from life→A vacuum flask has a double wall with a vacuum between the walls, and its inner wall is shiny. The vacuum stops conduction and convection, and the shiny surface reduces radiation.

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