Dust and Smoke in air Video Lecture - Class 6

dust and smoke we all know that air is a
mixture of several gases like oxygen
nitrogen carbon dioxide and inert gases
air also contains minut particles of
dust and smoke the following activity
demonstrates the presence of these minut
particles in air this experiment can be
performed in your house here is a boy
sitting inside his room by switching off
the lights and shutting all the doors
and windows
he made the room extremely dark he
opened the front door slightly to allow
a thin beam of light he observed that
this thin beam of light highlighted the
presence of many dust particles in the
air which were continuously in motion
this random moment is termed as Brownian
motion dust and smoke form a minor
constituent of air the amount of dust
and smoke in the air varies from place
to place they are inhaled by humans
through the nose during respiration but
the particles are prevented from
reaching the lungs as they are blocked
in the nostrils by fine hairlike
structures this is one of the reasons
why one shouldn't respire through the
mouth these particles are present in
large number where there is a lot of
pollution