用图1所示电路测量小灯泡的电阻和电功率，电源电压为4.5V，小灯泡L的额定电压为2.5V。滑动变阻器的规格为“50Ω 1.5A”。

  

                                                                                                                                                                                                                      

序号	U/V	I/A	R/Ω
1	1.0	0.18	5.56
2	1.5	0.22	6.82
3	2.0	0.25	8.00
4	3.0