Relate 1 kWh and SI unit of energy.

State the law which governs the amount of heat produced in a metallic conductor when current is passed through it for a given time. Express this law mathematically.

Name two common materials, used as heating elements.

You are given three bulbs of 40 W, 60 W and 100W. Which of them has lower resistance?

Mention two special features of the material used as an element of an electric iron.