Question

Activity
14.2
Place a candle in a beaker or wide-
mouthed bottle and light it. Light an
incense stick and take it to the mouth
of the above bottle (Figure 14.1).
Which way does the smoke flow when
the incense stick is kept near the edge
of the mouth?
Which way does the smoke flow when
the incense stick is kept a little above
the candle?
Which way does the smoke flow when
the incense stick is kept in other
regions?​

Answer 1

Explanation:

Activity:

1) Place a candle in a beaker or wide- mouthed bottle and light it.

2) Light an incense stick and take it to the mouth of the above bottle.

3) Place the incense stick near the edge of the mouth of the beaker, observe the direction of flow of smoke.

4) Then, place the incense stick a little above the candle and observe the direction of flow of smoke

5) We observe that, the smoke of the incense stick, held above the candle goes in upward direction. This is because, the air above the candle is hot and lighter. While the air at the edges of the beaker is comparatively cooler, so the smoke goes slightly upwards and then spreads in downward direction.

6) These patterns of flow of smoke reveal that air currents are caused by uneven heating of air.