已知R1:R2=3:4,當電R1、R2串聯(lián)在電路中時,R1、R2兩端的電壓之比U1:U2= ;當電阻R1、R2并聯(lián)在電路中時,在相同的時間內電流通過R1、R2所產生的熱量之比Q1、Q2= .
【答案】
分析:(1)兩電阻串聯(lián)時通過它們的電流相等,根據(jù)歐姆定律求出R
1、R
2兩端的電壓之比;
(2)兩電阻并聯(lián)時它們兩端的電壓相等,根據(jù)Q=W=
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t求出在相同的時間內電流通過R
1、R
2所產生的熱量之比.
解答:解:(1)當電R
1、R
2串聯(lián)在電路中時,通過兩電阻的電流相等,
∵I=
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,
∴R
1、R
2兩端的電壓之比:
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=
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=
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=
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;
(2)當電阻R
1、R
2并聯(lián)在電路中時,兩電阻兩端的電壓相等,
∵Q=W=
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t,
∴
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=
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=
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=
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.
故答案為:3:4;4:3.
點評:本題考查了串聯(lián)電路的電流特點和并聯(lián)電路的電壓特點以及歐姆定律、焦耳定律的靈活應用,靈活運用相關知識是關鍵.