$A$ voltmeter of resistance $150 \Omega$ connected across a cell of e.m.f. $3 \ V$ reads $2.5 \ V$. What is the internal resistance of the cell (in $Omega$)?

If three bulbs $60\,W$,$100\,W$ and $200\,W$ are connected in parallel,then

All wires have the same resistance $r$. The equivalent resistance between $A$ and $B$ is $R$. Now,if the keys $K_1$ and $K_2$ are closed,what will be the new equivalent resistance?

Consider the diagram shown below. $A$ voltmeter of resistance $150\,\Omega$ is connected across $A$ and $B$. The potential drop across $B$ and $C$ measured by the voltmeter is $...........\,V$.

$A$ thermocouple of resistance $1.6\,\Omega$ is connected in series with a galvanometer of $8\,\Omega$ resistance. The thermocouple develops an e.m.f. of $10\,\mu V$ per degree temperature difference between two junctions. When one junction is kept at $0\,^{\circ}C$ and the other in a molten metal,the galvanometer reads $8\,mV$. The temperature of the molten metal,when e.m.f. varies linearly with temperature difference,will be ............ $^{\circ}C$.

$A$ bulb rated $30\,V, 90\,W$ is to be operated on a $120\,V$ supply. What resistance (in $\Omega$) must be connected in series with it?