When you go back and forth with a candle, the flame always moves in the opposite direction first. If you hold a glass over the flame, that is not the case. Then the flame immediately moves in the right direction.
Answer
Bye Dieter
The flame doesn’t move in the opposite direction, it just hangs in the air around it. That air does not move (or very little) with the candle if you move it back and forth without glass above it. It’s a bit like your hair or scarf “goes back” when you ride a fast bike. The hair or scarf does not go back, of course, but is also kept a bit more “on the spot” due to the air that is around it and that remains in place. In the end it will last, because the flame hangs on the candle of course, and your hair and your scarf on you, but the air holds it back a bit. Just look at the top of the flame as you move it back and forth without glass above it. The top of the flame will not go any more to the right than it started from when you move the candle to the left.
The flame clings to the moving candle, but feels inhibited by the surrounding air. If you now hold a glass above the candle, you ensure that the surrounding air moves with the candle, so you do not have that inhibiting effect, the flame simply moves with the candle and air.
Answered by
ir Ineke De Coninck
Doorniksesteenweg 145 8500 Kortrijk
http://www.vives.be
.