The resistance of an ideal voltmeter is

An infinite sequence of resistors is shown in the figure. The resultant resistance between $A$ and $B$ will be,when $R_1 = 1\,\Omega$ and $R_2 = 2\,\Omega$ ............. $\Omega$

The resistance of the filament of an electric bulb changes with temperature. If an electric bulb rated $220\,V$ and $100\,W$ is connected to a $(220 \times 0.8)\,V$ source,then the actual power consumed would be:

The potential difference across $A$ and $B$,i.e.,$V_A - V_B$,is ......... $V$.

In the circuit shown in the figure,if the potential at point $A$ is taken to be zero,the potential at point $B$ is ................ $V$.

$A$ $100\, V$ voltmeter of internal resistance $20\, k\Omega$ in series with a high resistance $R$ is connected to a $110\, V$ line. The voltmeter reads $5\, V$. The value of $R$ is ................ $k\Omega$.