Question

In the experiment to determine the galvanometer resistance by half-deflection method, the plot of $\frac{1}{ \theta}$ vs the resistance (R) of the resistance box is shown in the figure. The figure of merit of the galvanometer is .............. ×10–1 A/division. [The source has emf 2V]

Answer 1

Using the equation:

$i = K\theta,$

At half deflection:

$\frac{2}{G + R} = K\theta.$

Rearranging:

$\frac{1}{\theta} = \frac{(G + R)K}{2} = RK + \frac{GK}{2}.$

From the slope of the graph:

$\text{Slope} = K = 0.5 = 5 \times 10^{-1} \, \text{A/division}.$