电工原理习题答案2269(第三章 8)(46-58)(2)

??－j(?C)UUS2这时，＝?23?Uj5G?C?j(?C)33?(1R61?)3US??1135()2?()RR6R6129

网孔法：??11??1?????I?Im2?U??m1S?GjωωG????1??111??1????I???I??m1?GGjωω?m2GIm3?0G????1??111?????I???m2??Im3?0GGGjωω????Im31?USG21?0Gj?c10?0G?111??0Gj?cG1211???GGj?cG11110???GGGj?c??1?????US?G?211?Gj?c1?G??21????Gj?c????2?11??1????Gj?c????G??????1?????US?G?22?21??1????Gj?c????G?????2?11????Gj?c???????1??1?2?2???????2R?R??R3R??????j?C??j?C?j?C?????R2?UR3?5R2??C?2?6R1?j?Cωωj??C?3S2

6

??1I??RI??而U2m3m3G?R3?USR?35R??c?26R21??j?cj??c?3?与U?反向，故有上式分母虚部为零时,U2S6R21??0j?Cj??C?311得：6R? ?CR?6??C?2?UR3R312这时：??3??3?5R29U3R?30RSR???C?2

3―52 105.8V 1R??10??0L?100?3―53 100?10?3 L?0.1592mHC?159.2pF

Q?100

3―54

22???1100??2?R????1L???????L10???1???22??1100??2????R???3L??L?????10?3???得R?5?1?100?L??8.66?100?C由?1?200?L??8.66200?C?得C?183.8?FL?27.57mH3―55

由1LC解得：C?183.8?F?105L?120?103RCf?70.7HzL?105?100RL?27.57mH 7

3―56

I0?IRLR22R???L?U??1.935A22R???L?U?0.4493AIC???L?IR0?1.882A3―57

谐振时?m?Z??0?1?j?C1L1j?L．j?C21L?a?Z?1???11j?C1j?C1j?L?j?C2L?jj?C2??01j?C2L?j?21L??C2?C1?1得：?0??b?Y??1?j?L11j?L2?j?C1?0谐振时?m?Z??01?j?L11j?L2?j?C1C??L2?L1?

3―58

得：?0?R?j?L?R??L?2?Zi?10?j20???10?2?2?R?j?l?R???L????由谐振条件：?m?Z??0 20??L??R2??L??20R2?02?R2??L???j??20?R2???L?2???R2??L?R???L?22?20?0106L2?500R2?L?R2?0L?500R2??500R?22?4R2?1062?1068

由题意，只有一个L能使电路谐振，所以 500R2得R?4? 则L?4?10?3HR??L?2??2?4R2?106?0?Zi?10?R2???L?2?10?4?4?10.5?16?16 9