Which uses more energy, a $250 \,W$ $TV$ set in $1 \,hr$ or a $1200 \,W$ toaster in $10$ minutes?

Draw a schematic diagram of a circuit consisting of a battery of three cells of $2\, V$ each,a $5 \,\Omega $ resistor,an $8\,\Omega $ resistor,and a $12\,\Omega $ resistor,and a plug key,all connected in series.

What are the advantages of connecting electrical devices in parallel with the battery instead of connecting them in series?

What is the highest and lowest total resistance that can be secured by combinations of four coils of resistance $4 \,\Omega, 8 \,\Omega, 12 \,\Omega$ and $24 \,\Omega$?

Calculate the number of electrons constituting one coulomb of charge.

$A$ copper wire has a diameter of $0.5\, mm$ and a resistivity of $1.6 \times 10^{-8}\, \Omega \, m$. What will be the length of this wire to make its resistance $10\, \Omega$? How much does the resistance change if the diameter is doubled?