A galvanometer having a coil resistance of `60 Omega` shows full scale defection when a current of `1.0 A` passes thoguth it. It can vbe convered into an ammeter to read currents up to `5.0 A` by

Options

A. putting in parallel a resistance of `240 Omega`
B. putting in series a resistance of `15 Omega`
C. putting in series a resistance of `240 Omega`
D. putting in parallel a resistance of `15 Omega`

Answer

D

Explanation

To convert a galbonmeter to ammeter to ammrter a small resistance is connected in parallel to the coil of the galvanometer.n
Here, `G_(1) = 60 Omega I_(g) = 1.0 A, I = 5A`
`I_(R) G_(1) = (1 - 1_(g))S`
`S = (I_(g) G_(1))/(I - I_(g)) = (1)/(5 - 1) xx 60 = 15 Omega`
Putting `15 Omega` resistance in parallel.