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What resistance has to have a voltmeter for measuring  ,with precision p=1%, the...

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solvedphyz | Student, College Freshman | (Level 1) Honors

Posted June 30, 2009 at 12:58 AM via web

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What resistance has to have a voltmeter for measuring  ,with precision p=1%, the voltage on resistor R=1KOhm.

Between points A and B, passes a constant current.

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giorgiana1976 | College Teacher | (Level 3) Valedictorian

Posted June 30, 2009 at 5:15 AM (Answer #1)

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The mesured resistance value and the real one are:

Rm=U/I

R=U/(I-Iv)=U/(I-(U/Rv))=Rm/(1-(Rm/Rv))

Rm=R/(1+(R/Rv))

The relative error is:

p=(R-Rm)/R=1-(1/1+(R/Rv))

Rv=R(1-p)/p=99KOhms

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