When a shunt of `4Omega` is attahced to a galvanometer, the deflection reduces to `(1)/(5)`th. If an additional shunt of `2Omega` is attached. What will be the deflection?

Options

A. `(1)/(10) `th of initial
B. `(1)/(13)` th of initial
C. remains the same
D. one of these

Answer

B

Explanation

Initial condition

When shunt of `4 Omega ` is used,
`(1)/(5) xx G = (4)/(5) i xx 4`
`implies G = 16 Omega`
When additional shunt of `2 Omega` is attached,
`i . xx 16 = (i - i .) (4)/(3)`
`12 i . = i - i.`
`implies i . = (1)/(13)`


It will reduce to `(1)/(13)` of the initial value.