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如图所示,匀强电场场强E=100V/m,A、B两点相距10cm,A、B连线与电场线夹角为60°,则UBA之值为(   )                                                                                                                             

                                                                                                                

    A. ﹣10V       B. 10V   C.                  ﹣5V      D. ﹣5V

                                                                                                                                     

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