阻值为2千欧、额定功率为1/4瓦的贴片电阻阻值...

来源：蜘蛛抓取(WebSpider) 时间：2011-10-06 06:57 标签： 贴片电阻阻值
这是个机器人猖狂的时代，请输一下验证码，证明咱是正常人~这是个机器人猖狂的时代，请输一下验证码，证明咱是正常人~1个4欧的电阻,与一个用电器串联在6伏电源两端,现在只知道用电器的实际功率为2瓦,则通过用电器的电流强度可能是多少?
sb湿白0012
设4欧的电阻为R1,用电器为R2.因为串联电路的电流相同,所以可得：I1＝U1/R1＝U1/4I2＝P2/U2＝2/U2因I1＝I2,所以U1/4＝2/U2,则U1*U2＝8 1式因串联电路的总电压等于各用电器电压之和,得：U1+U2＝6 2式将1式和2式联立,可得一个一元二次方程,U1＝2或U1＝4代入方程,可得：I＝0.5A或I＝1A其实二楼的方法也是正确的,只是写得简略了一点.
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其他类似问题
设电流为I,用电器电阻为R,列方程得，I^2*R=2I(4+R)=6解得I=1，或I=1/2.
电阻的功率：Pr=I^2R=4I^2电源输出的功率：P=UI=6I用电器的功率：P'=2w根据能量关系，有：Pr+P'=P即：4I^2+2=6I也就是，I^2-6I+2=0解这个关于I的一元二次方程，可得，I=0.25A，或I=1A
I^2*R+P=U*I 代入4*I^2+2=6I I=1A等式两边是功率相等。
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