为了测量一个“12V、5W”的小灯泡在不同电压下的功率,给定了以下器材:电源:电动势12V,内阻不计;安培

2025-03-16 11:24:04
推荐回答(1个)
回答1:

(1):由于实验要求电压从零调,所以变阻器应采用分压式接法;
由于小灯泡电阻较小满足
R
R
R
R
,电流表应用外接法,实验电路如图所示:

(2):电流表每小格读数为0.02A,应进行
1
2
估读,所以读数为:I=0.40A;
从U-I图象中可读出I=0.40A时对应的电压U=6.0V,所以小灯泡功率为:P=UI=2.4W;
(3):根据R=
U
I
可知,电阻R等于U-I图象中图线上的点与原点连线的斜率而不是切线的斜率,所以乙同学正确.
故答案为:(1)如图
(2)0.40,2.4
(3)乙

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