A range of galvanometer is V, when `50Omega` resistance is connected in series. Its range gets doubled when `500Omega` resistance is connected in series. Galvanometer resistance is

Options

A. `100 Omega`
B. `200 Omega`
C. `300 Omega`
D. `400 Omega`

Answer

D

Explanation

Let I be the maximum current in the galvanometer of resistance G. then `I=V_1/R_1=V_2/R_2` In this case, `V_I=V,V_2=2V,R_1=G+50 and R_2=G+500 therefore V/(G+50)=(2V)/(G+500)therefore 2(G+50)=G+500 therefore 2G+100=G+500 therefore G=400Omega`.