[{"data":1,"prerenderedAt":73},["ShallowReactive",2],{"q-fire-113-1-fire-science-029":3},{"subject":4,"subjectSlug":5,"subjectKicker":6,"subjectShort":7,"question":8,"related":27,"sameNumber":52,"hasEssay":26},"火災學概要","fire-science","火災學 · Fire Science","火災學",{"id":9,"webId":10,"year":11,"session":12,"subject":4,"number":13,"stem":14,"options":15,"answer":20,"answerNote":21,"images":22,"imagesPending":23,"lawTimestamp":11,"explanation":24,"explanationDeep":25,"freq":12,"indexable":26},"fire-113-1-火災學概要-029","fire-113-1-fire-science-029",113,1,29,"火場中的單位長度光學密度為 1 m-1 時，此火場中的發光物體之能見度約為多少公尺？",{"A":16,"B":17,"C":18,"D":19},"3","8","1.3","3.5","D",null,[],false,"本題考點：單位長度光學密度換算為減光係數，再套用發光性物體的能見度經驗式。\n【正解理由】依朗伯－比爾定律，煙層的單位長度光學密度 D 以常用對數定義，減光係數 Cs 以自然對數定義，兩者關係為 Cs = 2.303 × D。本題 D = 1 m⁻¹，故 Cs = 2.303 × 1 = 2.303 m⁻¹。發光性物體的能見度經驗式為 V = 8 ÷ Cs，代入得 V = 8 ÷ 2.303 ≈ 3.5 公尺，數值與選項相符，故選 D。\n【逐項排除】\n(A) 3 公尺係採反光性標示的係數 3，且未做對數換算，逕以 3 ÷ 1 求得，係數與換算兩處皆與本題條件不符。\n(B) 8 公尺係採發光性物體的係數 8 卻漏掉換算，把光學密度直接當成減光係數，逕以 8 ÷ 1 求得。\n(C) 1.3 公尺係完成換算但誤用反光性標示的係數，即 3 ÷ 2.303 約等於 1.3，適用對象錯誤。\n(D) 3.5 公尺為應選項，係數取 8 且已乘 2.303 完成換算，兩步驟皆正確。\n【記憶點】先把光學密度乘二點三○三化為減光係數，再記「發光取八、反光取三」除以減光係數。","能見度是煙控與避難安全驗證的核心參數，其理論基礎是朗伯－比爾定律：光線通過含煙介質時強度隨路徑長呈指數衰減，可寫成 I = I₀ × e 的負 Cs 乘 L 次方，其中 Cs 稱為減光係數，單位為每公尺。若改以常用對數描述同一衰減，得到的量即單位長度光學密度 D，定義為每公尺路徑上 I₀ 與 I 之比取常用對數的值。兩者的換算常數就是自然對數底與常用對數的比值，ln10 約等於二點三○三，故 Cs = 2.303 D。這個常數是本題唯一的關卡，漏掉它就會落到八公尺那個選項。\n\n能見度經驗式源自實驗歸納：對於自身會發光的標示，例如出口標示燈，能見度與減光係數的乘積約在五至十之間，取中間值八；對於必須靠環境光照射再反射入眼的標示，例如反光板或蓄光型標示，該乘積約在二至四之間，取中間值三。發光體之所以看得比較遠，是因為它不必依賴已被煙削弱的環境照度，只需自身光線穿透煙層一次。\n\n數值對照可以這樣記：減光係數零點一每公尺時，發光標示的能見度約八十公尺；減光係數一每公尺時約八公尺；減光係數二點三○三每公尺時約三點五公尺，正是本題的情形。\n\n易混淆概念對照：光學密度以常用對數定義，減光係數以自然對數定義，兩者只差 ln10 的比例，絕不可互相代入；能直接代進指數衰減式的是減光係數。相關考點延伸：同一組式子也用於由煙粒子的質量濃度與質量光學密度推算能見度，命題常改給質量濃度要求求能見度，計算順序仍是先得減光係數再取係數相除。",true,[28,32,36,40,44,48],{"webId":29,"stem":30,"number":31,"year":11,"session":12},"fire-113-1-fire-science-028","關於火場中生成的 CO 對人體的危害，下列敘述何者正確？",28,{"webId":33,"stem":34,"number":35,"year":11,"session":12},"fire-113-1-fire-science-030","有關煙控分析中「等效流動面積」的定義，下列敘述何者正確？",30,{"webId":37,"stem":38,"number":39,"year":11,"session":12},"fire-113-1-fire-science-027","火災發生後至閃燃發生的時間稱為閃燃時間（F.O.T.），影響閃燃時間的重要因素，下列何者錯誤？",27,{"webId":41,"stem":42,"number":43,"year":11,"session":12},"fire-113-1-fire-science-031","在電氣火災研究中，木材、電木等絕緣物中，受電氣火花而碳化，碳化部分會逐漸形成微量的結晶，而變成具有導電性，此現象稱為？",31,{"webId":45,"stem":46,"number":47,"year":11,"session":12},"fire-113-1-fire-science-026","有關燃燒上下限之敘述，下列何者正確？",26,{"webId":49,"stem":50,"number":51,"year":11,"session":12},"fire-113-1-fire-science-032","可燃物在大氣中僅因受熱致使溫度升高而引發燃燒的最低溫度稱為：",32,[53,57,61,65,69],{"webId":54,"year":55,"stem":56,"number":13},"fire-112-1-fire-science-029",112,"有關重油油槽發生火災時可能產生的大規模沸溢（boilover）現象，下列敘述何者錯誤？",{"webId":58,"year":59,"stem":60,"number":13},"fire-111-1-fire-science-029",111,"建築物內部裝潢材料對閃燃時間（F.O.T.）的影響，下列敘述何者錯誤？",{"webId":62,"year":63,"stem":64,"number":13},"fire-110-1-fire-science-029",110,"工廠使用之乙炔（C2H2），為防止爆炸引起火災，常利用裝有某化學物質與多孔性物質充填物之鋼瓶加壓保存，請問該化學物質為何？",{"webId":66,"year":67,"stem":68,"number":13},"fire-109-1-fire-science-029",109,"有關防火塗料敘述，下列何者錯誤？",{"webId":70,"year":71,"stem":72,"number":13},"fire-108-1-fire-science-029",108,"煙霧的流動為由高壓處往低壓處流，因此加壓造成壓力差可以有效控制煙霧流動。若於一安全梯間流入體積流率為 Q(m3\u002Fs)的空氣，形成 P 的壓力差，現欲將壓力差提高到 2P，則流入的空氣體積流率應為多少？",1785129966341]