A 20-kΩ/V voltmeter reads 10 V full scale,(a) What series resistance is required to make the meter read 50 V full scale?(b) What power will the series resistor dissipate when the meter reads full scale?

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Accepted Answer

20 kΩ/V = sensitivity = [latex] \frac { 1 }{ { I }_{ fs } } [/latex]
[latex] i.e.,{ I }_{ fs }=\frac { 1 }{ 20 } K\Omega /V=50\mu A [/latex]
The intended resistance [latex] { R }_{ m }=\frac { { V }_{ fs } }{ { I }_{ fs } } =10(20K\Omega /V)=200K\Omega [/latex]
(a) [latex] { R }_{ n }=\frac { { V }_{ fs } }{ { i }_{ fs } } -{ R }_{ m }=\frac { 50V }{ 50\mu A } -200K\Omega =800K\Omega [/latex]
(b) [latex] P={ I }_{ fs }^{ 2 }{ R }_{ n }={ (50\mu A) }^{ 2 }(800)=2mW [/latex]

Question : A 20-kΩ/V voltmeter reads 10 V full scale,(a) What series re...

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