实验报告(双臂电桥测低电阻)

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x 6=4.978

x??xi/n? 4.980

i?1n???xi?x/?n?1??0.008654

i?1n?n?2?A??xi?x/??n?1?*n??0.003366

i?1??2铜棒的B类不确定度与合成不确定度:

μA=0.003366 tP=1.11 c=3 Δ0=0.002

μB=Δ0/c=0.000667 kp=1

U

0.68??tP*?A???kP*?B??0.002659

22三、40cm铜棒电阻R的测量与数据处理:

铜(40cm)Ω 1600.03 1600.01 1601.31 1601.32 1600.08 1600.04 精品资料

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(1)平均值和A类不确定度:

n=6 x1=1600.03

x2=1600.01

x 3=1601.31 x 4=1601.32 x 5=1600.08 x 6=1600.04

x??xi/n? 1600.465

i?1n???xi?x/?n?1??0.0000021

i?1n?n?2?

A??xi?x/??n?1?*n??0.000008

i?1??2(2)实验仪器带来的系统误差(B类):

n=6 a=0.002 b=0.005 R=1600.465

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δ=?(a%+n*b/R)= ?0.0002564895 UR=R*δ=?0.295635

(3)R的合成不确定度:

μA=0.000008 UR=0.295635

U??A2?UR?20.295635

四、40cm铜棒电阻率的数值计算和数据处理:

40cm铜棒电阻率的计算:

L=0.40 d=0.00498 R=1600.465 R1=1000 Rn=0.001

Rx=(R/ R1) Rn=0.001600465

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ρ=πd2 Rx/4L=7.79564e-8

电阻率的不确定度传递公式:

SLlnDURxln2Dddd24DRxRxUdd2Udd2RxLDLLURxRxURxRx2

U2ULLULL2 =0.069e-8

因此,实验测得铜棒电阻率为

ρ= (7.796±0.069)×10-8Ω/m

五、30cm铜棒电阻率的数值计算和数据处理:

铜(30cm)Ω 1200.31 1197.42 1120.01 1199.52 1197.31 1197.01

30cm铜棒电阻率的计算:

L=0.30 d=0.0498 R=1185.26

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R1=1000 Rn=0.001

Rx=(R/ R1) Rn=0.00118526 ρ=πd2 Rx/4L=7.69563e-8

六,40cm铝棒电阻率的数值计算和数据处理

40cm铝棒电阻率的计算:

L=0.40 d=0.04996 R=704.32 R1=1000 Rn=0.001

Rx=(R/ R1) Rn=0.00070432 ρ=πd2 Rx/4L=4.600300e-8

于是得到结果:

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