To decrease the range of an ammeter its resistance need to be incrased an ammeter has resistacne `R_(0)` and range / which of the following resistance can be connected in series with it to drecease its range to `l//n`

Options

A. `(R_(0))/(n)`
B. `(R_(0))/(n-1)`
C. `(R_(0))/(n+1)`
D. none of these

Answer

D

Explanation

A galvanometer can be coinverted into an ammeter by using a low resistance wire is parallel with the galvanometer the range of ammeter can be increased but cannot be decreased the reason is theat a sereis resistor cannot change the current that will produce full deflection
Ashunt connected in parallel is given by
`S=(l_(g)G)/(l-k_(g))`
if `l lt l_(g)` then the value of S is negative hence a galvanometer cannot be converted into an ammeter of range `l lt l_(g)`