大物实验二级双臂电桥测低电阻

5物理三实验题目：双臂电桥测低电 学号：实验目的实验仪器实验原理56RnRin1、R由图5和图6GIG=0,CDI1RI3RXI1等，根 定律，可得方程组1

I3RnI2IIRIRR

RR RR

R2

R1

R3R RxRn的接触电阻Rin1Rix2Ri

RRXnX140cmR1，R2为10003x2R，再求x40cm15（2不做数据处理及结论Rn=0.001Ω,0.01级 R1=R2=1000Ω,0.02级 ΔL估40cm铜30cm铜40cm铝R(R(12345640cm先推导的计

R nR1 RRDRX

4RS

(D)2 R1613.111611.911610.211609.631609.536

1610.67D4.970mm4.970103m；L40cm0.4m RRn中R与R成线性关系，因此 RnR，即先算各次R均值后算R与XRX XRX 算各次RX再求平均完全等价

RnR

611.1103RR

(现计算R的不确定度(R(R n(nn55nUA n

0.611B类不确定度

(a%

nb)RR=1610.56Ω通过6个旋钮，n=6;准确度0.02级，则6相对误差(0.02

)则UB0.021610.560.322P0.683合成不确定度n

1.,( P UR

(tU)2(kU)2(1.110.611)2 (1.110.611)2 Rn(kp1P相对误差R则 0.01%0.0010.00001,P0.683RnR1(kp1P1相对误差(0.02

)则UB0.0210000.2P0.683现计算D的不确定度(D(D n(nn5nUA n

1.450103mmB类不确定度则UB

c

0.0010.3310-3mm,(c3,P0.683)3合成不确定度(n6,tp1.11kp1PtpU tpU k22 4501.1032()0.

现计算L的不确定度单次测量A类不确定度为零，只有B类不确定度

0.20.067cm,(c3,P0.683)3 RR现由R1

推导不确定度传递R

nR n

n 12

系数值写成不确号U

URUR12UDUL成标 n) n)2 R)2 1)24 D)2URUURUURDLL

U

n) n)2 R)2 1)24( D)2URUURUURDLL

(0.01%)2

)2

1.64310320.06744)

U

U

7.8121081.8731031.4631010(m),P0.6837.8120.015)108mP0.68330cmR1213.251211.351212.011211.621211.656

D4.970mm4.970103m；L30cm0.3m

RnR0.0011211.931.212103X XRR

3.14151211.930.001(4.970103

(1(7.8127.8371087.825108240cmR747.36747.35747.27745.37745.406

746.35D4.959mm4.959103m；L40cm0.4m

RnR0.001746.357.464103X XRRD

3.1415746.350.001(4.959103

实验小结及建议生，以及实验过程中外界的干扰，都会造成误