part 1: A galvanometer has a coil with a resistance of 81 W. A current of 131 mA causes full scale deflection. Calculate the value of the series resistor that is required in order to use the galvanometer as a Voltmeter with 40 V full scale.(adsbygoogle = window.adsbygoogle || []).push({});

so to make a voltmeter, the galvanometer and resistor have to be in series. so for the equivilant resistor i would have R+Rg=Reg

so by kirchoff's rules (loop rule) i conclude that the V=0 for the entire loop

Vo-ReqI=0

Vo=(R+Rg)I

40=(R+81)1.31

and with this i am getting a negitve number for R..please help

part 2: What shunt resistor is necessary to convert the galvanometer into an Ammeter which deflects full scale for 1.1 A?

so for an ammeter, the resistor and galvanometer are in parallel

Req=(1/R+1/Rg)^-1

and i am going to use the loop rule again.

Vo=RegI

Vo=I(1/R+1/Req)^-1

40=1.1(1/R+1/81)^-1

and i also get a negtive number...please help

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# Galvanometer has a coil with a resistance

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