A galvanometer having a resistance of $4 \Omega$ is shunted by a wire of resistance $2 \Omega$. If the total current is $1.5 \mathrm{~A}$, the current passing through shunt is

Let $G$ be the resistance of the galvanometer and $S$ be the resistance of the shunt.

Given $G = 4 \Omega$ and $S = 2 \Omega$.

The total current $I = 1.5 \mathrm{~A}$ divides into the galvanometer current $I_g$ and the shunt current $I_s$ such that $I = I_g + I_s$.

Since the galvanometer and shunt are in parallel, the potential difference across them is equal:

$I_g G = I_s S$

$I_g (4) = I_s (2)$

$I_g = 0.5 I_s$

Substituting this into the total current equation:

$0.5 I_s + I_s = 1.5$

$1.5 I_s = 1.5$

$I_s = 1 \mathrm{~A}$

Answer: $1 \mathrm{~A}$