Question

A galvanometer of internal resistance 100$\Omega$ has a full scale deflection current of 1mA. To convert it into a voltmeter of range 0-10V, the resistance to be connected is :

• A. $9000\Omega$ in Series
• B. $10,000\Omega$ in Series
• C. $9,900\Omega$ in Series
• D. $9,800\Omega$ in Series

Answer 1

The correct option is C $9,900\Omega$ in Series

$\frac{V_1}{V_2}=\frac{R_1}{R_2}$
but $V_1={iR}_1=1\times {10}^{-3}\times 100=0.1$
= $\frac{0.1}{10}=\frac{100}{100+x}$
$x=9900\Omega$