What is the cause of resistance?

If $10$ bulbs of $100 \ W$ each are kept on for $1 \ \text{hour}$, how much electrical energy is consumed?

$A$ child has drawn the electric circuit to study Ohm's law as shown in the figure. His teacher told him that the circuit diagram needs correction. Study the circuit diagram and identify the errors,then describe the correct circuit configuration.

What are solutions that conduct electricity called?

$A$ heater is joined in parallel with a $60\, W$ bulb and connected to the mains. If the $60\, W$ bulb is replaced by a $100\, W$ bulb,will the rate of heat produced by the heater be more,less,or remain the same?

Give reasons for the following:
$(i)$ Tungsten is used almost exclusively for the filament of electric lamps.
$(ii)$ Why do we use copper and aluminium wires for the transmission of electric current?