The Italian delegation of Science on Stage 2

The shadow of the flame and other hands-on experiments on the candle, inspired to Faraday and Leonardo

Abstract

A science show of a collection of experiments on the candle. They are taken from the book The Chemical History of a candle by Faraday, revised with the modern technology and the exceptional early work by Leonardo. A candle: its flame and its cup. Why are the edges much cooler than the part within? The wick and the capillarity. The dark shadow of the bright flame, how to see steaming upward the ascending current of hot air using the sun or a overhead projector light: comparison between Fadaray's and Leonardo's description. Three flame's effects: water production up, soot in the middle; and wax vapour down. Carbon dioxide put out progressively three candle flames. How to take soot from a candle with a caress and with the trick of the cork. The candle catches fire again. Mechanical and magnetic action on a candle. Analogy between respiration of livings and the flame of a candle.

Description

The inspirations

There is not a law under which any part of this universe is governed which does not come into play and is touched upon in these phenomena. There is no better, there is no more open door by which you can enter into the study of natural philosophy than by considering the physical phenomena of a candle.

You may ... be fit to compare to a candle; ... you may, like it, shine as lights to those about you; that, in all your actions, you may justify the beauty of the taper by making your deeds honorable and effectual in the discharge of your duty to your fellow-men.

(Faraday, The chemical history of a candle, 1860 - 1861)

The scenes

• A candle: its flame and its cup; a quick comparison with a simple oil lamp.
• The candle wick and the capillarity, with a hands-on simulation.
• Why are the edges much cooler than the part within? How to see steaming upward the ascending current of hot air, using the sunlight or an overhead projector light.
• The dark shadow of the bright flame: a quick comparison between Fadaray's and Leonardo's descriptions.
• The flame is hollow: how to see it with a metallic net or with a little fork.
• Black and white smokes from the flame: a rapid change with a simple action of the hand.
• How to take soot from a candle with a caress and with the trick of the cork: the soot moustaches
• The characteristic smell of a church and the soot smell.
• Three flame effects: water production up, soot in the middle; and wax vapour down.
• Carbon dioxide puts out progressively three candle flames.
• Repulsive and attractive (magnetic and mechanical) actions on the flame of a candle.
• Shining laser into the flame: the soot particles of the flame don't scatter laser light.
• Shining laser into the wax: laser interference into the candle wax and speckles.

More details

A more detailed description about this topic is reported in this document.

This topic was treated during an Italian workshop (Calitri, near Avellino, August 2007). You are invited to see the photo gallery.

Photos