An ammetre is obtained by shunting a `30 Omega` galvanometer with a `30 Omega` resistance. What additional shunt should be connected across it to double the range ?

Options

A. `15 Omega`
B. `10 Omega`
C. `5 Omega`
D. none of these

Answer

A

Explanation

Total range is doubled. i.e., `4l_(g)`
Now shunt required is `S = (I_(g))/(4l_(g) - I_(g)) xx G = 10 Omega`
`(1)/(30) + (1)/(x) = (1)/(10)` or `x = 15 Omega`