Two wires $A$ and $B$ of equal lengths are connected in the left and right gaps of a metre bridge. The null point is obtained at $40 \ cm$ from the left end. If the diameters of the wires $A$ and $B$ are in the ratio $3:1$,what is the ratio of the specific resistance (resistivity) of $A$ to that of $B$ (in $:$)?

The experimental setup of a meter bridge is shown in the figure. If the null deflection point of the galvanometer is at distance $x$ from end $A$,what will be the new null point if the radius of the wire $AB$ is doubled?

$A$ resistance of $2 \Omega$ is connected across one gap of a metre-bridge (the length of the wire is $100 \text{ cm}$) and an unknown resistance,greater than $2 \Omega$,is connected across the other gap. When these resistances are interchanged,the balance point shifts by $20 \text{ cm}$. Neglecting any corrections,the unknown resistance is (in $Omega$)

In a meter bridge experiment to determine the value of an unknown resistance,first the resistances $2 \Omega$ and $3 \Omega$ are connected in the left and right gaps of the bridge and the null point is obtained at a distance $l \ cm$ from the left. Now when an unknown resistance $x \ \Omega$ is connected in parallel to $3 \ \Omega$ resistance,the null point is shifted by $10 \ cm$ to the right of the wire. The value of unknown resistance $x$ is . . . . . . $\Omega$.

In the given Wheatstone bridge (meter bridge) circuit,the galvanometer shows zero deflection. The value of the unknown resistance $R$ is ................. $\Omega$.

In a sensitive meter bridge apparatus,the bridge wire should possess: