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Light and sound wave diagram in different mediums with different density

  • Writer: Evan Toh
    Evan Toh
  • Sep 30, 2024
  • 1 min read

Light and sound are both waves. So both carry energy from one place to another.


Light, which is part of the electromagnetic spectrum, is a transverse wave, It can travel through a vacuum at speed 3.0 x 108 m/s. As the light travels from an optically less dense medium (air) to an optically denser medium (liquid or glass), the light undergoes refraction and bends towards the normal due to a decrease in speed.


Light: Optically less dense medium to denser medium: 

– speed decreases

– wavelength shorter

– frequency remains constant


Sound is a longitudinal wave. It requires a medium to pass through and it cannot pass through a vacuum. Opposite to light, as the sound travels from a less dense medium (air) into a denser medium (water or solid), the speed increases.


Sound: Less dense medium to denser medium:

– speed increases

– wavelength longer

– frequency remains constant


Refers to the image below to understand how the waves behave in different mediums.



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