What will be the equivalent resistance of the circuit between $x$ and $y$?

Twelve wires of equal length and equal cross-sectional area form a cube. If the resistance of each wire is $R$,then the effective resistance between the two ends of a diagonal is:

Two resistances of $400 \Omega$ and $800 \Omega$ are connected in series with a $6 \text{ V}$ battery of negligible internal resistance. $A$ voltmeter of resistance $10000 \Omega$ is used to measure the potential difference across the $400 \Omega$ resistor. The error in the measurement of potential difference in volts is approximately:

The equivalent resistance between the points $A$ and $B$ is (in $\Omega$):

Of the two bulbs in a household circuit,one glows brighter than the other. Which of the two bulbs has a larger resistance?

In the circuit shown in the figure,no current flows through the ideal ammeter. If the internal resistance of the cell is negligible,the value of unknown resistance $R$ is .............. $\Omega$.