What is convection current?

What is thermal convection ? Briefly explain how are convection currents set up in water ?

Statement- 1 : Coolant coils are fitted at the top of a refrigerator , for formation of convection current. Statement- 2 : Air becomes denser on cooling.

What are conventional current and electronic current?

(a) What is an electric current? What makes an electric current flow in a wire? (b) Define the unit of electric current (or Define ampere).

Explain the formation of convection currents.