$A$ cylindrical metallic wire is stretched to increase its length. If the resistance of the wire is increased by $4 \%$, then the percentage increase in its length is (in $\%$)

The length of a hollow tube is $5\,m$,its outer diameter is $10\,cm$,and the thickness of its wall is $5\,mm$. If the resistivity of the material of the tube is $1.7 \times 10^{-8} \,\Omega m$,then the resistance of the tube will be:

By increasing the temperature,the specific resistance (resistivity) of a conductor and a semiconductor,respectively,is:

The electric resistance of a certain wire of iron is $R$. If its length and radius are both doubled,then

Two wires of the same material are given. The first wire is twice as long as the second and has twice the diameter of the second. The resistance of the first will be

$A$ nichrome wire $50 \text{ cm}$ long and $1 \text{ mm}^2$ cross-section carries a current of $4 \text{ A}$ when connected to a $2 \text{ V}$ battery. The resistivity of the nichrome wire in $\Omega \cdot \text{m}$ is: