In the given circuit diagram, a connecting wire of negligible resistance is joining the points $\mathrm{B}$ and $\mathrm{D}$, the current in the connecting wire is 

If the ammeter in the given circuit reads $2 \mathrm{A}$, the resistance $R$ is

The value of current $I$ in the circuit will be,

Consider the circuit below. The bulb will light up if:

In the circuit, wire $1$ is of negligible resistance. Then