题目内容
将规格分别为“50V,100W”和“50V,50W”的甲、乙两根电阻丝串联起来,接入一电源两极,为了安全,则该电源最大电压不能超过( )
A.50V | B.75V | C.100V | D.150V |
(1)电阻阻值R1=
=
=25Ω,R2=
=
=50Ω;
电阻的额定电流I1=
=
=2A,I2=
=
=1A;
(2)两电阻串联时,流过电路的电流I=I2=1A,
电源最大电压U=I(R1+R2)=1A×(25Ω+50Ω)=75V;
故选B.
| ||
P1 |
(50V)2 |
100W |
| ||
P2 |
(50V)2 |
50W |
电阻的额定电流I1=
P1 |
U1 |
100W |
50V |
P2 |
U2 |
50W |
50V |
(2)两电阻串联时,流过电路的电流I=I2=1A,
电源最大电压U=I(R1+R2)=1A×(25Ω+50Ω)=75V;
故选B.
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