With a resistance R connected in series with a galvanometer of resistance 100`Omega`, it acts as a voltmeter of range 0 to 10 V. To double the range a resistance of 1000 `Omega` is to be connected in series with R. Then the value of R `(inOmega )` is

Options

A. 1100
B. 1000
C. 900
D. 800

Answer

C

Explanation

If galvameter of resistance G, showing full scale deflection by current I_(g), when converted into a volumeter of range V, the resistance R in a series is R=`(V)/(I_(g))-G`
here ,R=`(10)/(I_(g))-100`
R+1000=`(20)/(I_(g))-100`
Solving(i)and (ii) , we get R=900`Omega`