兩題PHY `有關heat既..

angel

2008-03-16 5:04 am

1).Wrapping food with aluminium foils slows down evaporation from the foo d.Explain briefly how this singnificantly helps in keeping food warm.

2). When food is wrapped with aluminium foils for baking . Which surface of the foil ( dull or shiny surface ) is better to face outwards ? Explain.

thx for your help =] 幫幫手丫

回答 (1)

Audrey Hepburn

2008-03-16 6:59 am

✔ 最佳答案

1. The wrapping aluminium foils help slows downevaporation from the food. Hence less heat is loss through the evaporation ofwater since some energy will be loss by the latent heat of vaporization ofwater.

P.S. Aluminium foils also help reduce heat loss byradiation as it has a shiny surface. Shiny surface is a poor radiator.It also helps reduce heat loss by convection of fluid (air).

2. A shiny surface is desirable to face outside since itis a poor radiator of heat. So that less energy (heat) is lost to thesurrounding by radiation.

參考: Myself~~~

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