A red laser light beam in a dust-free dark room is invisible until chalk dust is dusted along its path. Why…

A red laser light beam in a dust-free dark room is invisible until chalk dust is dusted along its path. Why does the beam become visible?
  1. Chalk dust makes the laser light change direction from straight to curved
  2. Chalk dust particles scatter and reflect the straight light rays toward our eyes
  3. Chalk dust acts as a new luminous energy source
  4. Laser beams cannot travel straight without physical support

Solution

Light traveling in straight lines is invisible unless reflected off physical particles like dust directly into an observer's eyes.

Asked in: Homi Bhabha Practice

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