A range of galvanometer is V, when `50Omega` resistance is connected in series. Its range gets doubled when `500Omega` resistance is connected in series. Galvanometer resistance is

Options

A. `100 omega`
B. `200 omega`
C. `300 omega`
D. `400 omega`

Answer

D

Explanation

A galvanometer is converted in to a voltmeter when a high resistance is coinnected to it in series
It / is maximum current floweing through galvanometer then
`V=(R+G)l+(50+G)l…(i)`
where V is range of galvanometer
when `R =50 omega` is coinnected in series with it and G is galanometer resistance
when `500 omega` resistance is connected in series the range on dividing Eqs i by ii we get
`(V)/(2V)=(50+G)/(500+G)`
or `500+G=100+2G rarr G =400 omega`