Answer the given question in your own words:
Will the laser beam be seen if it passes through a glass box which contains a lighted incense stick?

Explanation

Scattering of light is required/necessary, for a ray of light to be visible. For this, the light rays should get scattered on hitting the tiny particles in its path. There are tiny particles of the incense stick scattered in the closed glass box, due to which the laser rays get scattered. These scattered rays enter our eyes and the laser beam is seen.