A、R<sub>1sub>>R<sub>0sub> B、R<sub>1sub><R<sub>0sub> C、R<sub>1sub>=2R<sub>0sub> D、R<sub>1sub>=R<sub>0sub>
A、R<sub>1sub>>R<sub>0sub> B、R<sub>1sub><R<sub>0sub> C、R<sub>1sub>=2R<sub>0sub> D、R<sub>1sub>=R<sub>0sub>
A、R<sub>1sub>烧坏,R<sub>2sub>不会烧坏 B、R<sub>1sub>、R<sub>2sub>均烧坏 C、R<sub>1sub>未烧坏,R<sub>2sub>烧坏 D、R<sub>1sub>、R<sub>2sub>均未烧坏
A、R<sub>1sub><R<sub>2sub> B、R<sub>1sub>>R<sub>2sub> C、R<sub>1sub>=R<sub>2sub> D、R<sub>1sub>≤R<sub>2sub>
A、R<sub>1sub>烧坏,R<sub>2sub>不会烧坏 B、R<sub>1sub>,R<sub>2sub>均烧坏 C、R<sub>1sub>未烧坏,R<sub>2sub>烧坏 D、R<sub>1sub>,R<sub>2sub>均未烧坏
A、(R<sub>1sub>+R<sub>2sub>)/R<sub>1sub>R<sub>2sub> B、R<sub>1sub>R<sub>2sub>/(R<sub>1sub>+R<sub>2sub>) C、R<sub>1sub>+R<sub>2sub> D、R<sub>1sub>R<sub>2sub>
A、图示的轴由两个角接触球轴承支承,轴承承受的径向载荷为R<sub>1sub>=1000N,R<sub>2sub>=2000N,轴向载荷F<sub>Asub>=900N,方向向右,载荷系数f<sub>Psub>=1.35。轴承的接触角α=25°,判断系数e=0.68。当A/R≤e时,x=1,y=0;当A/R>e时,x=0.41,y=0.87。派生轴向力S=0.7R。 r /> (1)计算轴承1上的当量载荷P<sub>1sub>;r /> (2)计算轴承2上的当量载荷P<sub>2sub>。r /> rc="https://img.ppkao.com/2018-09/wenxueying/2018090609333298275.jpg" />r />
A、电路如图所示,已知稳压管的稳定电压为6V,最小稳定电流为5mA,允许耗散功率为240mW;输入电压为20~24V,R<sub>1sub>=360Ω。试问:r /> (1)为保证空载时稳压管能够安全工作,R<sub>2sub>应选多大?r /> (2)当R<sub>2sub>按上面原则选定后,负载电阻允许的变化范围是多少?r /> rc="https://img.ppkao.com/2018-09/yuanhao/20180911103835413.jpg" />
A、R<sub>1sub>>R<sub>2sub>>R<sub>3sub> B、R<sub>1sub><R<sub>2sub><R<sub>3sub> C、R<sub>1sub>>R<sub>3sub>>R<sub>2sub> D、R<sub>3sub>>R<sub>1sub>>R<sub>2sub>
A、顺磁质μ<sub>rsub>>0,抗磁质μ<sub>rsub><0,铁磁质μ<sub>rsub>>>1 B、顺磁质μ<sub>rsub>>1,抗磁质μ<sub>rsub>=1,铁磁质μ<sub>rsub>>>1 C、顺磁质μ<sub>rsub>>1,抗磁质μ<sub>rsub><1,铁磁质μ<sub>rsub>>>1 D、顺磁质μ<sub>rsub><0,抗磁质μ<sub>rsub><1,铁磁质μ<sub>rsub>>0