I had a physics exams today and it was asking whether or not a shiny surface aluminium blanket was suitable to keep the sleeper warm. I put that because it's a conductor of electricitiy, heat loss will be greater so it wont be suitable for keeping him warm. On the other hand, some other people said that because it had a shiny surface, thus a good reflector of heat, it would be suitable for keeping him warm. Are both arguments correct?
Electrical conductivity has nothing to do with it. Emergency blankets of the type you describe have much lower thermal conductivity than metallic aluminium. The shiny surfaces both reflect body heat back to the body and do not radiate heat away. The sun is not involved in its operation as they work equally well at night or in other unlit places.
it will only keep you warm if you're in the sun. if you're in the dark then you're whistling Dixie Allan, you taught me something new, thank you :)
Metals are reflective for the comparable reason that they habit electrical energy. The steel has an excellent number of electrons that are very loosely guaranteed to the atoms; they are in a position to leap from one atom to a distinctive very quite. that's virtually like a sea of electrons. Electrons soak up photons of sunshine then re-emit them in random instructions, that's stated as scattering. you are able to think of that if the electrons emit the photons in random instructions then the floor could be boring white, no longer vivid, yet in reality so long as a results of fact the floor irregularities on the steel are smaller than a wavelength of sunshine each and all of the photons entering into extraordinary instructions cancel one yet another out, in simple terms leaving those that leap off on the comparable attitude they arrived at - mirrored photograph in different words. Metals are literally sparkling. you are able to locate that frustrating to have self belief yet once you're finding at an liquid crystal reveal reveal screen you're finding by using a layer of steel now - it varieties electric powered circuits on the returned of the glass reveal. Any cloth that reflects easy additionally transmits it. while the electrons are greater efficient at interacting with the photons of sunshine the fabric is greater reflective, as in a steel; while fewer electrons are interacting with the easy the fabric is greater transmissive, like glass or water. yet observe that cup and water the two mirror easy besides as transmit it.
