The current inside a copper voltameter:

Two bulbs of equal wattage,one having a carbon filament and the other having a tungsten filament,are connected in series to the mains. Then:

In the circuit given below,if the bulb is to glow with maximum intensity,the value of $R$ is (neglect internal resistance of the cell) (in $Omega$)

Thirteen resistances,each of resistance $R \, \Omega$,are connected in the circuit as shown in the figure below. The effective resistance between $A$ and $B$ is

The terminal voltage of the battery, whose emf is $10 \, V$ and internal resistance is $1 \, \Omega$, when connected through an external resistance of $4 \, \Omega$ as shown in the figure is: (in $V$)

The resistance between points $A$ and $B$ is