燈泡熱量問題可足以做成火警嗎

Let's do a simple calculation
Assume the piece of paper is of 10 g (=0.01 kg) mass, area 10 x 10 cm^2 (= 0.01 m^2), with specific heat capacity = 1400 J/kg-K
Further assume that 90% of the power consumed by the light bulb turns into radiant heat and which is emitted equally in all directions.

Heat given out in 24 hours
= 100 x 0.9 x 24 x 3600 J = 7 776 000 J
If the piece of paper is ta distance of 10 cm (=0.1 m) from the bulb, thermal energy received by the paper
= 7776000 x 0.01/(4 x pi x 0.1^2) J = 619 000 J

If initial temperature of paper = 23'C
temperature rise of paper = 619000/(0.01 x 1400) 'C = 44,000'C

The ignition temperature of paper is only 218'C. Hence, in theory, the paper would well be on fire.

However, the calculated result may probably not happen, as once the temperature of the paper rises, heat loss to the surroundings would also take place. The higher the temperature of the paper, the higher is the rate of jeat loss. Therefore, unless the surrounding air temperature also rises to hundreds of degrees, the paper could be on fire. But given the power of a 100w light bulb, it is hard to believe that it could heat up the air inside a small room up to hundreds of degrees

At a steady air temperature of 53'C quoted in your question, the paper temperature is far below than its ignition temperature. The paper would not catch fire.

Data on specific heat capacity and ignition temperature of paper can be found from the web-pages below:

http://www.engineeringtoolbox.com/specific-heat-solids-d_154.html

http://en.wikipedia.org/wiki/Autoignition_temperature

if you put the magnifying glass under the light bulb between the light bulb and the tissue,it may occured.

24小時開燈可能會使紙巾燒著

更多燈泡熱量問題,可參考效能

效能
大部分白熾燈會把消耗能量中的90%轉化成無用的熱能，只少於10%的能量會成為光。相比之下，螢光燈（Fluorescent lamp,亦稱光管）的效率高很多，接近40%，所產生的熱只是相同亮度的白熾燈的六分一。故此很多地方，特別是夏天需要空氣調節的商場、大樓都會使用螢光燈照明以節省電力。小型的螢光燈（節能燈泡）把螢光燈及啟動電子結合，使用標準電燈泡的接口，用以替代普通白熾燈泡。例如一個26瓦的節能燈泡，發出的亮度為11瓦，熱量為15瓦。發出相同亮度11瓦的白熾燈泡耗電多四倍，達100瓦；放出熱量多六倍，達90瓦。
很多家居內的電燈仍然是以普通白熾燈為主。鹵素燈泡近年亦變得較為流行，特別是光源需要集中的情況，例如家居的射燈，汽車車頭燈，經常會使用鹵素燈泡。良好的鹵素燈泡可以達到15%的效率。例如一個60瓦的鹵素燈泡，亮度可等同一個100瓦的普通燈泡。但是鹵素燈泡體積細小，運作時溫度非常高。在家居應用時需要特別防護，防止引起火災。
至於而戶外的街燈照明，以鈉燈（Sodium vapor lamp）最為常見。低壓鈉燈發出的是單調的橙色光線，但是它的效率卻非常高，比普通電燈泡高出約十五倍。高壓鈉燈色效率稍低，但顏色較為豐富。
最近數年的發展，則以發光二極管（LED）及高強度氣體放電燈（High Intensity Discharge　HID)照明開始流行。前者的優點是非常長壽，現已用在交通燈、以及手電筒之上。後者其實是多種技術的統稱(鈉燈亦屬於HID)。很多最新汽車使用的氙氣車頭燈(Xenon HID)、放映機使用的金屬鹵化物燈（Metal Halide），都是屬於HID。


圖片參考：http://imgcld.yimg.com/8/n/HA05305704/o/701001090037713873391710.jpg

有可能，但也不排除冇，如果系24小時ge話，可能會燒著