Question

A galvanometer with a scale divided into $100$ equal divisions has a current sensitivity of $10$ divisions per milliampere and a voltage sensitivity of $2$ divisions per millivolt. The galvanometer resistance will be

• A. $ 4 \, \Omega$
• B. $ 5 \, \Omega$
• C. $ 3 \, \Omega$
• D. $7 \, \Omega$

Answer 1

The Correct Option is B

Given: current sensitivity = 10 div/mA and there are 100 division on the scale.
$\therefore$ Current required for full scale deflection.
$I_{g} = \frac{1}{10} \times100\,mA = 10 \,mA$
$ = 0.1 A $
Also voltage sensitivity = 2 div/mV
$\therefore$ voltage required for full scale deflection
$ V_{g} = \frac{1}{2} \times100mV $
$= 0.05V $
Galvanometer resistance is given by
$ G = \frac{V_{g}}{I_{g}} = \frac{0.05}{0.01} $
$= 5 \Omega $