Question

A galvanometer gives full scale deflection with `0.006 A` current. By connecting it to a `4990Omega` resistance, it can be converted into a voltmeter of range `0.30 V`. If connected to a `(2n)/249 Omega` resistance, it becomes an ammeter of range `0-1.5A`. the value of `n` is

Answer 1

`i_g(G+4990)=V`
`implies 6/1000(G+4990)=30`
`implies G+4990=30000/6=5000`

`G=10 Omega`
`V_(ab)=V_(cd)`
`i_gG=(1.5-i_g)S`
`implies 6/1000xx10=(1.5-6/1000)S`
`implies S=60/1494=(2n)/249`
`implies n=(249xx30)/1494`
`=2490/498=5`