標題: F.4 Phy??? [打印本頁] 作者: toy1018 時間: 23/12/2009 07:24 PM 標題: F.4 Phy??? The heating element in an electric kettle is fixed near the bottom. Explain why the water gets hot much more slowly if the heating element is fixed at the top. 好似明.....but唔知點解釋!!!! thx for ur help!!!!!!!!!作者: hk56740 時間: 23/12/2009 10:08 PM 本帖最後由 hk56740 於 2/1/2010 10:34 PM 編輯
because when you put it close to the bottom,you can heat the cool water at the bottom as hot water floats and cool water sinks, making a convection current.However, when you put it at the top, you can only heat the water at the top but the cool water at the bottom can't be heated.