The actual value of resistance R, shown in the figure is `30 Omega`. This is measured in an experiment as shown using the standard formula `R = (V)/(I)`, where V and I are the readings of the voltmeter and ammeter, respectively. If the measured value of R is 5% less, then the internal resistance of the voltmeter is

Options

A. `600 Omega`
B. `350 Omega`
C. `35 Omega`
D. 570

Explanation

`V_m=R_m j_m=j_R.R`
`implies R_m=(j_R times R)/j_m=R(r/(R+r))`
`implies 1/R_m=((R+r))/(Rr)=1/r+1/R implies 1/r=1/R_m-1/R = 1/(95 R)-1/R=1/R times 5/95 implies r=(30 times 95)/5=570 Omega`