3-1一台四极直流电机,元件数S=120,每元件电阻为0.2,当转速为1000r/min时,每元件的平 均电动势为10V。求当电枢绕组分别为单叠和单波时,正负电刷间的电压U和电枢绕组电阻R各 为多少?

1 Atomic Orbital Theory 1 2 Bonds Between Adjacent Atoms: Localized Bonding, Molecular Orbital Theory 25 3 Delocalized (Multicenter) Bonding 54 4 Symmetry Operations, Symmetry Elements, and Applications 83 5 Classes of Hydrocarbons 110 6 Functional Groups: Classes of Organic Compounds 139 7 Molecular Structure Isomers, Stereochemistry, and Conformational Analysis 221 8 Synthetic Polymers 291 9 Organometallic Chemistry 343 10 Separation Techniques and Physical Properties 387 11 Fossil Fuels and Their Chemical Utilization 419 12 Thermodynamics, Acids and Bases, and Kinetics 450 13 Reactive Intermediates (Ions, Radicals, Radical Ions, Electron-Deficient Species, Arynes) 505 14 Types of Organic Reaction Mechanisms 535 15 Nuclear Magnetic Resonance Spectroscopy 591 16 Vibrational and Rotational Spectroscopy: Infrared, Microwave, and Raman Spectra 657 17 Mass Spectrometry 703 18 Electronic Spectroscopy and Photochemistry 725