Why do we use copper and aluminium wire for the transmission of electric current?

An electric bulb rated $220 \, V, 60 \, W$ is working at full efficiency. $(i)$ State the resistance of the coil of the bulb. Another identical bulb is connected in series with the first one and the system is connected across the mains as shown below. $(ii)$ State the rate of conversion of energy in each bulb. $(iii)$ Calculate the total power. $(iv)$ What will be the total power if the bulbs are connected in parallel?

Define resistance of a conductor. State the factors on which resistance of a conductor depends. Name the device which is often used to change the resistance without changing the voltage source in an electric circuit.
Calculate the resistance of $50 \, m$ length of wire of cross-sectional area $0.01 \, mm^2$ and of resistivity $5 \times 10^{-8} \, \Omega \, m$.

The $SI$ unit of electric charge is $.........$

State $Ohm's$ law. How can it be verified?

Potential and potential difference are vector quantities.