網路會員
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我鍾意曬咸魚。天然生晒。再用風筒吹...哈。哈。哈。 |
網路會員
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咁抵死，幫你搽D天拿水，嘿嘿嘿！ |
網路會員
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你呢個無良奸商...想食壞人呀! |
網路會員
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無，想你食左high D而已！ |
網路會員
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不過。話時話。用風筒吹下支鏡就唔毛。呢個都幾得意。
將d塵吹晒入去就真...哈。哈。哈。 |
網路會員
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找個風扇吹住個溫度計，每跌一度我切一磅肉給你。
在溫度計上先塗點水或酒精再吹，則作別論。
不明白原理的話，可參考初中課本。
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天氣乾燥就唔知, 如果有番80% 濕度, 我諗你唔駛瘦身都可以輕幾磅.
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網路會員
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wuwi兄:
>>用風筒吹完可以令鏡頭溫度降低, 天氣潮濕時可能仲大件事.
此話何解? |
網路會員
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我估...佢係諗住溫度降低左,
o甘d水咪會在鏡面上"形"結....
其實,我都唔係好明"風筒吹完可以令鏡頭溫度降低".... @_@?
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網路會員
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唔駛咁驚, 皮旦最多無一兩磅肉姐, 唔會好多.
因為流動空氣會帶走能量, 但因為空氣既比熱容細, 所以可以帶走能量有限, 但如果潮濕時, 即空氣有大量水份, 水既比熱容大, 流動空氣可以帶走能量多, 所以溫度下降明顯d. 所以皮旦話唔可以加水就係咁解, 不過濕度高左同加左水分別唔大.
因為其他地方都係潮濕, 無風時呢濕氣咪又包圍住支鏡, 而且溫度低d 濕氣會難走d, 但又不至於凝結既.
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網路會員
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It is a common misconception in Physics.
It has nothing to do with latent heat capacity.
The point is: how come you get youy lens hotter than room
temperature? Secondly, how come you can lower the lens temperature
by using a hair-dryer?
When you blow the lens with air at room temp.,
the air does NOT take any heat away. Heat is taken away
by air only if the air is cooler than the lens. BUT,
if you blow the lens with cool air, still you can't
get the moisture away as long as the relative humidity is
the same within the lens and in your room.
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網路會員
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Arthur塗夫兄:
wuwi說的是Specific heat, 不是潛熱. |
網路會員
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thanks for the correction. |
網路會員
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Suggested answers:
>how come you get youy lens hotter than room temperature?
Maybe they've shot at outdoors with high temperature and take the gears back into an A/C room.
....
>BUT, if you blow the lens with cool air, still you can't get the moisture away as long as the relative humidity is the same within the lens and in your room.
Relative humidity is a funciton of temperature while moisture content is the same in this case. |
網路會員
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比熱容 specific heat capacity - the energy that can change the temp in 1 degree
比濳熱 specific latent heat - the energy to allow the material to change of state (soild, liquid or air)
我地睇到溫度一樣, 只不過係去到一個平衡點, 其實能量依然是不斷在轉換, 其實水既溫度唔會同空氣差太大, 咁點解有風先降溫呢.
雖然四周的濕度一樣, 但在鏡頭四周的水份被風帶走換來其他位置的水份. 所以水份是不斷轉換, 不凝聚而比較難去到一個平衡點.
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網路會員
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I'm still thinking about the driving force for energy exchange. If everything is in equilibrium (i.e. no temperature difference), I can't see the temperature will drop in either media. Moreover, most of the hair-dryer utilise the airflow generated by itself to cool down the motor and in turns the temperautre will be increased afterwards. So, I think Peter will gain weight rather than losing it. :) |
網路會員
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>>"咁點解有風先降溫呢"
1. 降溫
有風 not neccessary 會降溫. 風 can rise 溫 too!
有風先降溫 ONLY IF there is temperature difference between
the air blow and the thing being blown. That is, cooler air blwoing at something hotter.
Otherwise, no 降溫 at all if the air blown has the same temperature as the lens.
That's why I asked how you get a lens hotter than the air.
2. removing humidity
Also, if there is no difference in relative humidity between the media,
you can't remove humidity from one medium to another simply by blowing
it with air. Any air blown away will be replaced with the same amount of
air with the same amount of moisture.
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網路會員
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wuwi兄：
＞天氣乾燥就唔知, 如果有番80% 濕度, 我諗你唔駛瘦身都可以輕幾磅.
找支溫度計試左先講啦，雖然我多好想少幾磅肉（減極都有成200磅呀，陰功！）
有80%濕度都沒用，問題是風扇出來的風溫度及濕度均與與目標物相同，帶來的熱能與帶走者相同，不會影響溫度。
要迅速散熱，一方面風與目標物溫差要大（所以我說要燒紅支鏡頭），另外周遭環境要乾燥，而目標物有相當濕度，利用水的特大specific heat capacity藉蒸發帶走熱能。
返回正題。總之，有霉一定要抹得乾乾淨淨。此外，為了避免已經散步於鏡頭各處的胞子發芽，鏡頭在抹乾淨後仍應放在乾燥之處。個人在近年來一直用吸濕大笨象，效果蠻好，但也有聽到朋友打瀉藥液，因此應當小心。
最奇怪的是：鏡頭生產商為何不在鏡筒中使用煤焦油等防霉塗層防止發霉－－難道是有意的？ |
網路會員
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降溫, 係風+水份, 即係水份既流動, 測濕度都係用咁既方法, 用一支有濕棉既溫度計, 睇下個溫差來計出濕度, 但溫度計的濕棉係唔會比佢乾 (乾左溫度就會同番室溫一樣), 即係包住溫度計既濕度其實係一樣, 只不過空氣會帶走水份, 令水份有流動.
另外風唔係帶走濕度, 係唔比佢凝聚, 不斷比空氣中既水份流動.
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網路會員
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>>另外風唔係帶走濕度, 係唔比佢凝聚, 不斷比空氣中既水份流動.
Just another formulation of the original misconception.
Water condense or not depends on the amount of kinetic energy it possess,
not whether there is air float or not, esp. when there is no
temperature difference between the media.
Have you notice that we have much water on the floor in spring
even there is wind (esp. from the south) blowing?
Air float is not a physical variable in the present issue.
As far as I know, the fact is: no Physics textbook ever consider air float as a
variable for formulating thermo-physical laws. |
網路會員
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what is "air float"? |
