Question

The deflection in a moving coil galvanometer falls from 50 divisions to 10 divisions,when a shunt of $2?$ is connected with it. The resistance of galvanometer coil is

• A. $24?$
• B. $12?$
• C. $6?$
• D. $48?$

Answer 1

Answer: (D)

$48?$

Answer 2

Let the value of current for one division of galvanometer is i.
Then the current through the ammeter (1) = 50 i
and current through the galvanometer $(I_g) = 10 i$
We know that
$S = \frac{I_g}{(I - I_g)} G$
$\Rightarrow G = S \bigg(\frac{I - I_g}{I_g} \bigg)$
$= 12 \times \bigg[\frac{50i - 10i}{10i} \bigg]$
$= 12 \times \bigg[\frac{40i}{10i} \bigg] = 48?$