Question

The range of an ammeter of resistance 'G can be increased from 'l' to 'nl' by connecting.

Options

• a series resistance of `"G"/("n + 1") Omega`

• a shunt of `"G"/("n - 1") Omega`

• a shunt of `"G"/("n + 1") Omega`

• a series resistance of `"G"/("n - 1") Omega`

Answer 1

a shunt of `"G"/("n - 1") Omega`

Explanation:

The range of an ammeter can be increased by connecting a shunt or parallel resistance to it, whose value is given by

R = `("l"_"g"/("l" - "l"_"g")) "G" Omega`    ....(i)

To increase the range from Ito nl, the current passing through it is I = nl_g

Using this value in Eq. (i), we get

R = `("l"_"g"/("n" "l"_"g" - "l"_"g"))"G"`

`= "G"/("n - 1") Omega`