- Remove the cover of shoe box and place the box on its side.
- Cut two holes of half inch diameters on the top of box and a window on one side of the box.
- Roll two pieces of stiff paper and paste the edges to make two cylinders.
- Insert the cylinders into the two holes in the box.
- Now cover the open side of the box with a transparent polythene sheet, pasting it along the edges.
- Insert a small lighted candle through the window and place it below chimney 2. Shut the window and bring a smoking dhoopbatti near chimney 1.
- You will see that smoke from dhoopbatti is drawn into the box through chimney 1. It travels through the box and comes out of chimney 2.
Conclusion:-The air near the burning candle gets heated, expands, becomes lighter, rises and goes out of chimney 2. This make the air and smoke from the dhoopbatti rush in through chimney 1 to fill up the space thus created. The mixture of air and smoke gets heated by the candle and goes out through chimney 2. Thus convection current is setup.
Concept used in daily life:-
Day: The land is warmer than the ocean. The warm air over the land rises and the cooler air over the ocean sinks and rushes in underneath to fill the space. This heat
transfer by a circulation of rising warm air (less dense) and sinking cooler air (denser) creates air currents with an onshore breeze.
Night: The water cools off more slowly than the land and the air above the water is slightly warmer than over the land. The warmer air over the water rises and the cool air over the land sinks which creates air currents with an off shore breeze.
