Question

A galvanometer has a resistance of G ohm and range of V volt. Calculate the resistance to be used in seres with it to extend its range its renge to nV volt.
A. nG
B. `(G)/(n)`
C. `(n-1)G`
D. `(G)/(n-1)`

Answer 1

Correct Answer - C
A high resistance is connecte in series with coil of the galvanometer to convert it into voltmeter
Resistance connected in series is given by
`R=(V)/(l_(g))-G`
Eq (i) is the value of the resistance required to convert the galvanometer to voltmeter it into voltmeter
Resistance conected in series is given by
`R=-(V)/(l_(g))-G=(nV)/(V//G)-G`
or `R=nG-G=G(n-1)`
hence `R=(n-1)G`