Thursday, November 27, 2008

Physics of Flame

Deep Physics lies hidden in simple phenomena around. This week, let's see what a candle flame can teach us:

21nov 009 

When I take photos of the candle flame through my Kodak Easy Share C533 camera, I get different photos on different settings. This Kodak Digital camera is a simple point and shoot camera. Same candle showed up as follows in another picture:

21nov 010

Q.1: Compared to the first picture, why is there so much sideways glow in this picture?




Q.2: Why is the shape of the candle flame like a tapering upwards always?

Q.3: What would be the shape of candle flame, in place where there is no gravity?

I took further close up photographs of candle flame with my Kodak Digital Camera. Here is the picture:

21nov 015

Q.4: Do you see the color distribution between blue and yellow? What gives rise to the two colors? What decides the position of these two colors in the flame?





To verify whether its a feature only 21nov 020of wax candle flame, I took photograph of a glowing matchstick:

It also shows the similar features, indicating the same Physics governing.

Answers below[can you spot them? :) ]  :-

Ans.1. the glow captured in the camera depends on the exposure setting. The molecules are exciting and de-exciting at a rapid rate. The de-excitation is very fast, 10^(-8)sec, but the excitation depends on the temperature in that region. In the second photo, wider region is captured, indicating larger exposure time.

Ans.2.Fluid dynamics of simple laminar flow... Its same to the flow of water when you open it at very slow speeds. This is flow below the Reynolds number. Above Reynolds number, the flow is chaotic, as can be seen in the case of smoke from an incense. 

Ans.3.Sphere !? :) that's my guess... 

Ans.4.higher temperatures give higher excitation and de-excitation, resulting in blue. Only two colors are seen corresponding to energy levels available. the position shows the temperature profile.


L. Venkata Subramaniam said...

I thought you were going to give some reasons for why the flame is the way it is?

Abhay Karnataki said...

Sure! But I am waiting for some guesses by the readers! Why do you think the flame is the way it is!