would you expect to take more time or less time to boil water in a saucepan if the outside curved surface of the saucepan were polished chrome rather than dull black? explain.
my guess is black takes a shorter time because it is a better absorber of heat. polished chrome is shiny which makes it a good reflector and a bad radiator. or does polished chrome take a shorter time since it does not radiate much heat? come to think of it, chrome seems to take a shorter time.
pretty perplexed by all these colours and stuff. can someone explain?
This depends greatly on the method of heat transfer. Your explanation due to the colour applies only if radiation is the dominant path for heat transfer.
In the case of the saucepan over the fire, we can expect the following:
1) Conduction
Not very great because of the layer of air between the flame and the saucepan.
Air is a bad medium for heat transfer by conduction.
2) Convection
Some convection exists, but not a lot as compared to radiation. This is because the distance between the flame and the saucepan is too short.
Radiation is a much more effective method of heat transfer.
3) Radiation
As mentioned in (2), radiation should be the dominant pathway for heat transfer in this case.
Thus, we will expect a dull black surface on the outside of the saucepan to boil water faster than that of a polish chrome.
Anyway.... Saucepans are usually black in colour, I believe. It is pots that have more silver colours... mainly because they are used to maintain the heat of things like soups within them...
Regards,
Eagle
Owner of Strategic Tuition