In the following circuit, the magnitude of current $I_1$, is ______ $\mathrm{A}$.

 

The equivalent resistance between $A \text{and} B$ is _______.

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If the potential difference between $B$ and $D$ is zero, the value of $x$ is $\frac{1}{n} \mathrm{\Omega }$. The value of $n$ is ______.

A water heater of power $2000 \mathrm{W}$ is used to heat water. The specific heat capacity of water is $4200 \mathrm{J} {\mathrm{kg}}^{-1} {\mathrm{K}}^{-1}$. The efficiency of heater is $70\%$. Time required to heat $2 \mathrm{kg}$ of water from $10°\mathrm{C}$ to $60°\mathrm{C}$ is _____ $\mathrm{s}$.

(Assume that the specific heat capacity of water remains constant over the temperature range of the water).

The equivalent resistance between $A and B$ of the network shown in figure: