Three voltmeters,all having different internal resistances,are connected as shown in the figure. When a potential difference is applied across $A$ and $B$,their readings are $V_1, V_2$,and $V_3$. Choose the correct option.

Two wires of the same material have lengths in the ratio $1 : 2$ and radii in the ratio $2 : 1$. If they are connected in parallel to a battery,what is the ratio of heat produced in them?

Resistances $R_1$ and $R_2$ are joined in parallel and a current is passed so that the amount of heat liberated is $H_1$ and $H_2$ respectively. The ratio $\frac{H_1}{H_2}$ has the value:

When a resistor of $11 \Omega$ is connected in series with an electric cell,the current flowing in it is $0.5 \ A$. Instead,when a resistor of $5 \Omega$ is connected to the same electric cell in series,the current increases by $0.4 \ A$. The internal resistance of the cell is (in $\Omega$)

If each resistance in the figure is $9 \Omega$,then the reading of the ammeter $(A)$ is (in $A$)

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?