Q 12-04-178JEE MainJEE Main 2020 (8 Jan, Shift 2)Easy
A galvanometer having a coil resistance $100\ \Omega$ gives a full scale deflection when a current of $1$ mA is passed through it. What is the value of the resistance which can convert this galvanometer into a voltmeter giving full scale deflection for a potential difference of $10$ V?
Answer: (D) $9.9$ k$\Omega$
A series resistance $R$ is needed so that $I_g(G + R) = V$:
$$R = \frac{V}{I_g} - G = \frac{10}{10^{-3}} - 100 = 9900\ \Omega = 9.9\ \text{k}\Omega$$
Solution by Sreeraj P, M.Sc Physics