Full-scale deflection occurs in a moving coil galavanometer of resistance `36 Omega` when 100 mA current flows through it. What arrangement should be done to convet it into a voltmeter of `0-5V` range ? Draw the ncessary circuit diagram.

Explanation

Resistance of the glvanometer `=36Omega`, maximum current `I_(G)=100 mA=0.1A`.
Connecting a resistance R in series with the glvanometer and using the equipment in between the two points A and B, we shall get voltemeter difference ranging from 0 to `(V_(A)-V_(B))` [Fig. 1.79]. Here `V_(A)-V_(B)=5Va`
Now `V_(A)-V_(B)=I_(G)(G+R)`
or, `R=(V_(A)-V_(B))/(I_(G))-G=(5)/(0.1)-36=50-36=14 Omega`
This is the required value of the resistance R.