In the experiment studying the dependence of current $I$ on the potential difference $V$, three students plotted the following graphs between $V$ and $I$. The graph that is likely to be correct is/are:

In the electrical circuit shown in figure, the potential across $4\mathrm{\Omega }$resistor is:

For a metallic conductor, current versus voltage graph is drawn at two different temperatures ${\mathrm{T}}_1$ and ${\mathrm{T}}_2$. From the graph it follows:

What will be the value of $\mathrm{R}$ in the following circuit? 

Seven identical lamps of resistance $220 \mathrm{\Omega }$ each are connected to a $220 \mathrm{V}$ line as shown in figure. Then the reading in the ammeter will be: