A moving coil galvanometer has 150 equal divisions. Its current sensitivity is 10-divisions per milliampere and voltage sensitivity is 2 divisions per millivolt. In order that each division reads 1 volt, the resistance in ohms needed to be connected in series with the coil will be -

Options

A. `9995 Omega`
B. `10^(3)Omega`
C. `10^(5)Omega`
D. `99995 Omega`

Answer

A

Explanation

Current senstivity=10 divisions/milliampere`therefore` Current flowing through the galvanometer for full scale deflection is`(150)/10=15 mA` and voltage senstivity=2divisions/millivolt. PgtD for division`=(150)/2=75` millivolt `therefore` Resistance=`(75 xx 10^(-3))/(15 xx 10^(-3))=5 Omega` For getting one volt/division or 150 V for full scale deflection, the resistance of the galvanometer should be `R=V/I=(150)/(15 xx 10^(-3))=10,000Omega`