冰箱所能做的只是轉(zhuǎn)移熱量或者說能量,從一個(gè)地方轉(zhuǎn)移到另外一個(gè)地方。
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Turn on your oven, and you'll warm up the kitchen. With the oven door open, the kitchen warms up even faster. That much is obvious since the purpose of an oven is to make things hot. But the opposite is not true of your refrigerator.
Running the refrigerator makes the room warmer and if you leave the door open, the kitchen warms up even faster. The first rush of cold air may cool things down a little, but in the long run, the room will get warmer.
To see why, we need to think of heat as energy and cold as a lack of energy. The stove produces heat, but the refrigerator can't actually produce cold. All the refrigerator does is move heat, or energy, from one place to another. As the food inside the refrigerator loses its heat–or, in other words, gets colder–that heat ends up in the kitchen.
Physicists call this kind of system a "heat pump." But like any motor, the heat pump in your refrigerator needs energy just to run. So while it's busy moving energy out of the fridge and into the kitchen, it's also drawing in more energy in the form of electricity or gas. Since some of that energy is released as heat, you end up with more heat in the kitchen than you started with.
打開微波爐,會使你的廚房變暖。當(dāng)把微波爐的門打開時(shí),廚房變暖的速度將更快。這是顯而易見的,因?yàn)槲⒉t的作用便是使物體變熱。但是這一理解用于相反的冰箱卻并不正確。
運(yùn)行中的冰箱使房間變暖,并且當(dāng)你把冰箱的門打開時(shí),廚房變暖的速度將更快。首先沖出的冷空氣也許會是物體降低些溫度,但是長遠(yuǎn)來看,房間的溫度會上升。
想知道原因,我們需要把熱看成具有能量而冷是缺乏能量。暖爐產(chǎn)生熱量,但是冰箱實(shí)際上并不能生成寒冷。冰箱所能做的只是轉(zhuǎn)移熱量或者說能量,從一個(gè)地方轉(zhuǎn)移到另外一個(gè)地方。當(dāng)冰箱里的食物丟失熱量或者說變冷的時(shí)候,熱量被釋放入廚房。
物理學(xué)家把這一系統(tǒng)稱作“熱泵”。但是像所有的發(fā)動機(jī)一樣,冰箱需要能量以排出熱量。因此當(dāng)將能量移出并排到廚房的時(shí)候,冰箱同樣需要從電或者氣中吸收更多的能量。而因?yàn)橐恍┠芰恳詿崮艿男问结尫?,因此冰箱制冷結(jié)束時(shí)會比開始時(shí)有更多的能量在廚房。