[{"data":1,"prerenderedAt":73},["ShallowReactive",2],{"q-fire-109-1-fire-science-006":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-109-1-火災學概要-006","fire-109-1-fire-science-006",109,1,6,"某次閃電的過程中，雲的底部和地面之間，電壓高達 1 千萬伏特，並在約 0.02 秒內輸送 20 庫倫的電量至地面。下列與閃電有關的敘述何者正確？",{"A":16,"B":17,"C":18,"D":19},"該次閃電所產生的電功率約為 107 瓦特","雲和地面間高電壓的產生與摩擦起電有關","飛機在空中飛行時不可能遭雷擊，因此不須裝置避雷針","閃電時的大電流，使空氣產生高熱而快速膨脹，故常伴隨有雷聲","D",null,[],false,"本題考點：閃電的電學基礎,包含電功率計算、雲層電荷分離機制與雷聲的成因。\n【正解理由】閃電通道在極短時間內通過數千安培的電流,焦耳熱使通道空氣瞬間升溫至數萬 K,空氣急速受熱膨脹形成衝擊波向外傳播,衰減後即為人耳聽到的雷聲。此為雷聲的標準成因,敘述完全正確,故選 D。\n【逐項排除】\n(A) 依電功率 P＝VI,電流 I＝Q\u002Ft＝20 C÷0.02 s＝1,000 A,故 P＝10⁷ V×10³ A＝10¹⁰ W,與選項所稱的 10⁷ 瓦特相差達一千倍,數量級錯誤。\n(B) 雲內電荷分離主要來自冰晶與霰粒碰撞的起電作用;雲與地面之間隔著空氣、並未接觸摩擦,兩者間的高電位差是帶負電雲底對地面產生靜電感應的結果,歸因於摩擦起電並不正確。\n(C) 飛機在空中確實會遭雷擊,機身金屬殼體形成導電籠將電流沿表面導出並經放電刷洩放,「不可能遭雷擊」與事實不符。\n(D) 大電流產生高熱、空氣爆炸性膨脹、形成衝擊波、傳為雷聲,因果鏈完整且正確,為應選項。\n【記憶點】先見閃電後聞雷:雷聲是空氣被電流瞬間加熱到爆開所產生的衝擊波。","本題把電學單位換算包裝成自然現象題,拆解後只有三個定義:電流是單位時間通過的電量(1 A＝1 C\u002Fs)、電功率是電壓與電流的乘積(1 W＝1 V×1 A)、能量是功率乘以時間。代入題給數據,電流 20 C÷0.02 s＝1,000 A,功率 10⁷ V×1,000 A＝10¹⁰ W,整次閃電釋放的能量約 10¹⁰ W×0.02 s＝2×10⁸ J,約合 4.8×10⁴ 千卡,足以在瞬間點燃接觸到的可燃物,這正是雷擊被列為天然火源的原因。\n雷擊引起火災的途徑分三類:直擊雷造成建物、樹木或油槽直接起火;感應雷在附近落雷時於金屬導體上感應出高電位,擊穿絕緣而引燃;雷電突波沿電力或通信線路侵入,燒毀設備並在配線上形成短路起火。避雷設備的原理不是「避開」雷,而是以尖端放電主動引雷,再經引下導體與接地極把電流安全導入大地,使電流不流經建築結構,概念與法拉第籠一致——飛機能承受雷擊也是同樣的殼體導流原理,因此 (C) 的說法站不住腳。\n易混淆對照:摩擦起電、感應起電與接觸起電是三種不同的起電方式。雲內冰晶碰撞屬摩擦與碰撞起電,使雲頂帶正電、雲底帶負電;雲底與地面之間則是靜電感應,使地面感應出正電荷,累積到空氣絕緣破壞(乾燥空氣約每公分 3 萬伏特)時放電。火災學另一個高頻考點是靜電火災,兩者同屬靜電累積後放電引燃,差別在能量尺度:靜電放電能量以毫焦耳計,只能點燃最小點火能量極低的可燃性氣體與粉塵,雷擊則是以巨大能量直接引燃固體可燃物,兩者的防護對象與手段完全不同。",true,[28,32,36,40,44,48],{"webId":29,"stem":30,"number":31,"year":11,"session":12},"fire-109-1-fire-science-005","下列有關二氧化碳（CO2）滅火劑之敘述，何者錯誤？",5,{"webId":33,"stem":34,"number":35,"year":11,"session":12},"fire-109-1-fire-science-007","進入石化工廠，車輛會被要求在排氣管加裝滅焰器（flame arrester）以避免火災爆炸之發生，加裝該措施防制火災爆炸之原理為：",7,{"webId":37,"stem":38,"number":39,"year":11,"session":12},"fire-109-1-fire-science-004","某一火災成長至 2,000 kW 所需時間為 400 秒，請問該火災屬何種成長性火災？[Q：釋熱率（MW）； 1\u002F2 t：經過時間（sec）；k：火災成長常數（sec\u002FMW ）]",4,{"webId":41,"stem":42,"number":43,"year":11,"session":12},"fire-109-1-fire-science-008","1 度電為 1,000 瓦．小時（1 kWh），試問 1 度電約等同多少千卡（kcal）？",8,{"webId":45,"stem":46,"number":47,"year":11,"session":12},"fire-109-1-fire-science-003","依用戶用電設備設置規則及建築技術規則，下列避雷設置敘述何者錯誤？",3,{"webId":49,"stem":50,"number":51,"year":11,"session":12},"fire-109-1-fire-science-010","有水之場所的插頭應加裝何種裝置以防止感電發生？",10,[53,57,61,65,69],{"webId":54,"year":55,"stem":56,"number":13},"fire-111-1-fire-science-006",111,"火災成長歷程中，下列何者非閃燃之現象？",{"webId":58,"year":59,"stem":60,"number":13},"fire-110-1-fire-science-006",110,"阿里山發生森林火災，已知火災當天的相對濕度為 60.0%，前一天相對濕度為 50.0%，再前一天相對濕度為 40.0%，試求火災當天的實效濕度？",{"webId":62,"year":63,"stem":64,"number":13},"fire-108-1-fire-science-006",108,"當受熱平面與熱輻射線方向垂直時，其輻射角為 0 度；兩者平行時，輻射角為 90 度。假設輻射源強度不變，當受熱平面由垂直逐漸傾斜，致使輻射角由 0 度增加至 60 度時，該平面所受的輻射熱通量變為原來的若干倍？",{"webId":66,"year":67,"stem":68,"number":13},"fire-107-1-fire-science-006",107,"危害物質災害現場搶救標準作業程序（H.A.Z.M.A.T.）之說明，下列何者為正確？",{"webId":70,"year":71,"stem":72,"number":13},"fire-106-1-fire-science-006",106,"通常可燃性氣體或液體之分子每莫耳燃燒熱大於多少 kcal\u002Fmole？",1785123162682]