Question

path traced by a single particle of smoke issuing from a incense stick is called

Answer 1

The path traced by such a particle is known as Brownian Motion.

The principle behind Brownian Motion is that, particles such as that issuing from a burning incense stick, do not have forces of attraction between themselves and hence move in a zig-zag random motion.

The theory of Brownian Motion was proposed by Albert Einstein, who is regarded as one of the Fathers of Modern Physics.