“PZ220-100”的燈泡接在220伏的電路上工作________小時消耗1度電,改接在110伏的電路中,額定功率為________瓦.若將甲燈泡“PZ220-100”、乙燈泡“PZ220-15”兩者串聯(lián)在220V電路中,則燈泡較亮的是________(選填:“甲”、“乙”或“一樣亮”)
10 10 乙
分析:(1)額定電壓下燈泡正常發(fā)光,根據(jù)t=
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求出消耗1度電所需的時間;
(2)根據(jù)R=
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求出燈泡的電阻,根據(jù)P=
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求出改接在110伏的電路中的實際功率;
(3)根據(jù)R=
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比較兩燈泡的電阻關(guān)系,根據(jù)串聯(lián)電路的電流特點和P=I
2R判斷兩燈泡的實際功率,再根據(jù)燈泡的亮暗取決于實際功率的大小判斷燈泡的亮暗.
解答:(1)燈泡正常發(fā)光時的功率為100W,
消耗1度電所需的時間t=
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=
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=10h;
(2)燈泡的電阻:
R=
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=
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=484Ω,
改接在110伏的電路中的實際功率:
P′=
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=
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=10W;
(3)根據(jù)R=
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可知,兩燈泡的額定電壓相等,PZ220-15燈泡的電阻大,
兩燈泡串聯(lián)時通過它們的電流相等,根據(jù)P=I
2R可知PZ220-15燈泡的實際功率較大,燈泡較亮.
故答案為:10;10;乙.
點評:本題考查了電功率公式的靈活運用,關(guān)鍵是知道燈泡正常工作時實際功率和額定功率相等.