如图所示,电源电压U为8V,定值电阻R2为4欧,小灯A上标有“4V,1W”,小灯B上标有“20V 10W ”的字样,电路接通后小灯A恰好正常发光,求 (1)小灯B的电阻RB (2)小灯B的实际功率PB (3)定值电阻R1的大
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![如图所示,电源电压U为8V,定值电阻R2为4欧,小灯A上标有“4V,1W”,小灯B上标有“20V 10W ”的字样,电路接通后小灯A恰好正常发光,求 (1)小灯B的电阻RB (2)小灯B的实际功率PB (3)定值电阻R1的大](/uploads/image/z/5368612-4-2.jpg?t=%E5%A6%82%E5%9B%BE%E6%89%80%E7%A4%BA%2C%E7%94%B5%E6%BA%90%E7%94%B5%E5%8E%8BU%E4%B8%BA8V%2C%E5%AE%9A%E5%80%BC%E7%94%B5%E9%98%BBR2%E4%B8%BA4%E6%AC%A7%2C%E5%B0%8F%E7%81%AFA%E4%B8%8A%E6%A0%87%E6%9C%89%E2%80%9C4V%2C1W%E2%80%9D%2C%E5%B0%8F%E7%81%AFB%E4%B8%8A%E6%A0%87%E6%9C%89%E2%80%9C20V+10W+%E2%80%9D%E7%9A%84%E5%AD%97%E6%A0%B7%2C%E7%94%B5%E8%B7%AF%E6%8E%A5%E9%80%9A%E5%90%8E%E5%B0%8F%E7%81%AFA%E6%81%B0%E5%A5%BD%E6%AD%A3%E5%B8%B8%E5%8F%91%E5%85%89%2C%E6%B1%82+%EF%BC%881%EF%BC%89%E5%B0%8F%E7%81%AFB%E7%9A%84%E7%94%B5%E9%98%BBRB+%282%29%E5%B0%8F%E7%81%AFB%E7%9A%84%E5%AE%9E%E9%99%85%E5%8A%9F%E7%8E%87PB+%EF%BC%883%EF%BC%89%E5%AE%9A%E5%80%BC%E7%94%B5%E9%98%BBR1%E7%9A%84%E5%A4%A7)
如图所示,电源电压U为8V,定值电阻R2为4欧,小灯A上标有“4V,1W”,小灯B上标有“20V 10W ”的字样,电路接通后小灯A恰好正常发光,求 (1)小灯B的电阻RB (2)小灯B的实际功率PB (3)定值电阻R1的大
如图所示,电源电压U为8V,定值电阻R2为4欧,小灯A上标有“4V,1W”,小灯B上标有“20V 10W ”的字样,电路接通后小灯A恰好正常发光,求
(1)小灯B的电阻RB
(2)小灯B的实际功率PB
(3)定值电阻R1的大小
如图所示,电源电压U为8V,定值电阻R2为4欧,小灯A上标有“4V,1W”,小灯B上标有“20V 10W ”的字样,电路接通后小灯A恰好正常发光,求 (1)小灯B的电阻RB (2)小灯B的实际功率PB (3)定值电阻R1的大
Ra=4²÷1=16Ω
Ia=4÷16=0.25a
UR2=0.25×4=1v
UB=4+1=5V
Rb=20²/10=40Ω
PB=5²÷40=0.625w
IB=5÷40=0.125a
I=0.25+0.125=0.375a
R₁=(8-5)÷0.375=8Ω
(1)因为连接电路后灯泡A恰好发光 所以UA=4V ,RA=U²/P=4²/1=16欧 (2)RB=U²/P=20²/10=20欧,因为此电路是并联电路,所以UB=UA=4V,PB=U²/R=4²/20=0·8W(3)I总=IA+IB=P/UA+P/UB=1/4+0·8/4=9/20A R1=U/I=4/9/20=80/9欧
RB=(20*20)/10=40;
IA=1/4=0.25A Ur2=0.25*4=1v UB=4+1=5V PB=5*5/40=0.625 IB=0.625/5=0.125A
RA=(8-5)/(0.25+0.125)=8