A `100 V` voltmeter of internal resistance `20 k Omega` in series with a high resistance `R` is connected to a `110 V` line. The voltmeter reads `5 V`, the value of `R` is

Options

A. `210 Komega`
B. `270 Komega`
C. `350 KOmega`
D. `420 Komega`

Answer

D

Explanation

Internal Resistance of the voltmeter coil,`i=110/(20 xx 10^(3)+R)` But the voltage developed across the voltmeter 5V `therefore 5=ix ` Resistance of voltmeter (R') `i=110/(20 xx 10^(3)+R)`.