Two copper wires A and B have the same length and are connected across the same battery. If $R_{B}=2 R_{A}$ find the ratio of their cross-sectional areas, $A_{B} / A_{A}$.

Two copper wires A and B have the same length and are connected across the same battery. If $R_{B}=2 R_{A}$ find the ratio of their resistivities, $\rho_{B} / \rho_{A}$.

Two copper wires A and B have the same length and are connected across the same battery. If $R_{B}=2 R_{A}$ find the ratio of the currents in each wire, $I_{B} / I_{A}$.

Two copper wires have the same length and the same temperature.However,the electric resistance of wire A is twice as large as the resistance of wire B.Explain how wire A and wire B are different.

Two wires A and B made of the same material and having the same lengths are connected across the same voltage source. If the power supplied to wire A is three times the power supplied to wire B, what is the ratio of their diameters?