A moving coil galvanometer has a voltage senstivity of I division per millivolt and current sentivity of 10 divisions per milliampere scale. What resistance should be connected in series with the galvanometer coil, so that it reads I volt per division?

Options

A. `10,000Omega`
B. `9,900Omega`
C. `9,990Omega`
D. `9,950Omega`

Answer

C

Explanation

For the M.C.G, galvanometer resistance (G) current senstivity/voltage senstivity `therefore G=(10"div"//mA)/(1"div"//mV)=10 Omega` The full scale deflection current (maximum current) that can be passed through the galvanometer`=(100)/10=10mA=I_g` and since there are 100 divisions, the voltage to be measured`=100 xx 1= 100 V`. `therefore` Total resistance of the voltmeter `V/I_g=(100)/(10 xx 10^(-3))=10^(4)Omega= 10,000 Omega therefore` The resistance in series that should be connected to the galvanometer`=10,000-10=9990 Omega`.