A、R=X<sub>Lsub>=X<sub>Csub> B、X<sub>Lsub>=X<sub>Csub>≠R C、X<sub>Lsub>>X<sub>Csub> D、X<sub>Lsub><X<sub>Csub>
A、R=X<sub>Lsub>=X<sub>Csub> B、X<sub>Lsub>=X<sub>Csub>≠R C、X<sub>Lsub>>X<sub>Csub> D、X<sub>Lsub><X<sub>Csub>
A、如题68图所示电路,运算放大器为理想运算放大器,已知U<sub>i1sub>=2V,U<sub>i2sub>=4V,R<sub>1sub>= R<sub>5sub>=10kΩ,R<sub>2sub>=20 kΩ,R<sub>3sub>= R<sub>4sub>=5 kΩ。求:r /> rc="https://img.ppkao.com/2018-09/tianmin/2018090510023683894.jpg" />
A、如题68图所示电路,运算放大器为理想运算放大器,已知U<sub>i1sub>=2V,U<sub>i2sub>=4V,R<sub>1sub>= R<sub>5sub>=10kΩ,R<sub>2sub>=20 kΩ,R<sub>3sub>= R<sub>4sub>=5 kΩ。求:r /> rc="https://img.ppkao.com/2018-09/tianmin/2018090510023683894.jpg" />
A、如图所示为R-L-C并联的正弦电路,已知R=50Ω、L=16mH、C=40μF,接于有效值为U=220V的工频电源上,试求I<sub>Rsub>、I<sub>Lsub>、I<sub>Csub>、I。r /> rc="https://img.ppkao.com/2018-05/tangxueping/2018051016121530201.jpg" />
A、图示三极管放大电路,已知U<sub>ccsub>=12V,R<sub>Csub>=5kΩ,三极管的β=100,r<sub>besub>=2.5kΩ,R<sub>Bsub>=1MΩ,U<sub>BEsub>忽略不计,C<sub>1sub>、C<sub>2sub>足够大。r /> rc="https://img.ppkao.com/2018-08/lina/2018082009234328254.jpg" />
A、如图所示,已知u=U<sub>msub>sinωt V,R,X<sub>Lsub>,X<sub>Csub>,电容电流大于电感电流,试画出电路中电压、电流的矢量图。rc="https://img.ppkao.com/2018-09/wangjing/2018092909095681515.jpg" />
A、以下所示的结构设计简图中,已知轴的转速n=1470r/min,角接触轴承1上的径向载荷R<sub>1sub>=800N,角接触轴承2上的径向载荷R<sub>2sub>=1900N,轴向载荷F<sub>asub>=1200N,两个轴承的额定动载荷C<sub>rsub>均为C<sub>rsub>=38600N,e=0.68,S=0.7R,A/R≤e,x=1,y=0;A/R>e,x=0.41,y=0.87,f<sub>tsub>=1.1,f<sub>psub>=1.2,求受载最大的轴承的工作寿命L<sub>hsub>。r /> rc="https://img.ppkao.com/2018-09/wenxueying/2018090609482576109.jpg" />
A、r<sub>1sub>=r<sub>2sub>=0,L<sub>1sub>=L<sub>2sub>=M=0 B、r<sub>1sub>=r<sub>2sub>=0,L<sub>1sub>=L<sub>2sub>=M=∞ C、r<sub>1sub>=r<sub>2sub>=∞,L<sub>1sub>=L<sub>2sub>=M=0 D、r<sub>1sub>=r<sub>2sub>=∞,L<sub>1sub>=L<sub>2sub>=M=∞
A、R<sub>1sub>〉R<sub>3sub>〉R<sub>2sub> B、R<sub>1sub>=R<sub>2sub>=R<sub>2sub> C、R<sub>1sub>〈R<sub>3sub>〈R<sub>2sub> D、都不对