A wire of resistance $$R$$ and radius $$r$$ is stretched till its radius became $$r / 2$$. If new resistance of the stretched wire is $$x ~R$$, then value of $$x$$ is ________.

A wire of resistance $$20 \Omega$$ is divided into 10 equal parts, resulting pairs. A combination of two parts are connected in parallel and so on. Now resulting pairs of parallel combination are connected in series. The equivalent resistance of final combination is _________ $$\Omega$$.

In the experiment to determine the galvanometer resistance by half-deflection method, the plot of $$1 / \theta$$ vs the resistance (R) of the resistance box is shown in the figure. The figure of merit of the galvanometer is _________ $$\times 10^{-1} \mathrm{~A} /$$ division. [The source has emf $$2 \mathrm{~V}$$]

Two wires $$A$$ and $$B$$ are made up of the same material and have the same mass. Wire $$A$$ has radius of $$2.0 \mathrm{~mm}$$ and wire $$B$$ has radius of $$4.0 \mathrm{~mm}$$. The resistance of wire $$B$$ is $$2 \Omega$$. The resistance of wire $$A$$ is ________ $$\Omega$$.