A voltmeter has a range `O - V` with a series resistance `R`. With a series resistance `2R`, the range is `O - V`. The correct relation between `V` and `V'`is

Options

A. `V' = 2 V`
B. `V' gt 2 V`
C. `V' gt gt 2 V`
D. `V' lt 2 V`

Answer

D

Explanation

(d) For conversion of galvanometer (of resistance) into voltmeter, a resistance `R` is connected in series.
`:. i_(g) = (V)/(R + G)` and `i_(g) = (V')/(2R + G)`
`implies (V)/(R + G) = (V')/(2R + G)`
`implies (V')/(V) = (2R + G )/(R + G) = (2 (R + G) - G)/((R + G))`
`2 - (G)/((R + G)) implies V' = 2V = (VG)/((R + G)) implies V' lt 2V`