A galvanometer with a scale divided into `100` equal divisions has a current sensitivity of `10` divisions per mA and a voltage sensitivity of `2` divisions per mV. What adoptions are required to read (i) `5A` for full scale and (ii) 1 division per volt?

Explanation

Full scale deflection `i_(g)=0/(cs)=100/10mA=10A`
Full scale deflection voltage `V_(g)=0/(vs)`
`=mv=50mv`
So galvanometer resistance `G=(50mV)/(10mA)=5Omega`
(a) To convert the galvanometer into an ammeter of range 5A, a resistance of volue `5Omega` is connected in parallel with it such that
`(I-i_(g))S=i_(g)G`
`(5-0.01)S=0.01xx5`
`S=5/(499)overset(~~)(=)0.01Omega`
(b) To convert the galvanometer into a voltmeter which reads 1 adivision per volt, i.e. of range 100 V,
`V=i_(g)(R+G)`
`100=10xx10^(-3)(R+5)`
`R=10000-5`
`R=9995Omegaoverset(~~)(=)9.995KOmega`