If a wire is stretched to make it $0.1 \%$ longer,its resistance will

Two square-shaped metal plates $A$ and $B$ of the same thickness $(t)$ and of the same material are connected as shown in the figure. The side of $B$ is twice that of $A$. If the resistances of $A$ and $B$ are $R_A$ and $R_B$ respectively, then $\frac{R_A}{R_B}$ is:

What is resistivity? Write its unit. On what factors does resistivity depend?

Assertion: Bending a wire does not affect electrical resistance.
Reason: Resistance of a wire is proportional to the resistivity of the material.

In order to quadruple the resistance of a uniform wire,a part of its length $x$ was uniformly stretched till the final length of the entire wire was $1.5$ times the original length $l$. The fraction of the wire that was stretched,$x/l$,is equal to:

What length of the wire of specific resistance $48 \times 10^{-8} \, \Omega \, m$ is needed to make a resistance of $4.2 \, \Omega$ (in $.1$)? (Diameter of wire = $0.4 \, mm$)