Traditional Culture Encyclopedia - Photography and portraiture - Candle shadow experiment?

Candle shadow experiment?

When air is heated, it will expand. Hot air and cold air are equivalent to two media through which light propagates, so light will be refracted when it propagates. When the light of the flashlight propagates in the hot air above the candle flame, it will not go straight ahead, but turn in other directions, so the hot air will leave a faint shadow on the wall.