In a linear two-port network, when $10$ V is applied to Port $1$, a current of $4$ A flows through Port $2$ when it is short-circuited. When $5$ V is applied to Port $1$, a current of $1.25$ A flows through a $1 \Omega$ resistance connected across Port $2$. When $3$ V is applied to Port $1$, the current (in Ampere) through a $2 \Omega$ resistance connected across Port $2$ is ________.