题目

如图所示的电路中,电源的电动势E和内电阻r恒定不变,电灯L恰能正常发光,如果变阻器的滑片P向b端滑动,则(   )                                                                                                                                                                                                                                                   A.  电灯L变亮,电流表的示数增大     B.  电灯L变亮,电流表的示数变小     C.  电灯L变暗,电流表的示数变小     D.  电灯L变暗,电流表的示数增大                                                                                                                                       答案:B
物理 试题推荐
最近更新