Dimensions of a block are $1 \, cm \times 1 \, cm \times 100 \, cm$. If the specific resistance of its material is $3 \times 10^{-7} \, \Omega \cdot m$,the resistance between the square faces is:

Why does the resistivity of a metal increase with an increase in temperature,or why does its conductivity decrease with an increase in temperature?

$A$ metal rod of length $10 \text{ cm}$ and a rectangular cross-section of $1 \text{ cm} \times 0.5 \text{ cm}$ is connected to a battery across opposite faces. The resistance will be . . . . . . .

The reciprocal of resistance is

At room temperature $(27^{\circ} C)$,the resistance of a heating element is $50 \Omega$. The temperature coefficient of the material is $2.4 \times 10^{-4} { }^{\circ} C^{-1}$. The temperature of the element,when its resistance is $62 \Omega$,is $\qquad$ ${ }^{\circ} C$.

The following figure shows cross-sections through three long conductors of the same length and material,with square cross-sections of edge lengths as shown. Conductor $B$ will fit snugly within conductor $A$,and conductor $C$ will fit snugly within conductor $B$. The relationship between their end-to-end resistance is: