Why does sound need a medium for transmission whereas the electromagnetic waves doesnt ?

Why does sound require a medium for transmission or propagation. But this is not the case with electromagnetic waves. Why?

Why does sound need a medium for transmission whereas the electromagnetic waves doesnt ?
Think of electromagnetic waves as two fields of force, one magnetic and at right angles to this an electric force field. These two fields are created and moving away from their source. They are complete in themselves and do not need to reach a target by influencing anything inbetween the source and target.





The ear responds to pressure waves in the the air. When the air changes from a force the ear detects it as sound. When you clap you affect the air molecules between your hands. These bump into the air molecules all around them and the enrgy is transferred down the line, molecule to molecule to your ear.





By nature sound is force transmitted through a medium to a detector that picks up the change in the medium. EM waves are fields that do not affect the medium but travel through and indpendent of it.
Reply:Sound waves require a medium to travel, because a sound wave is merely a compression that's transmitted through a medium such as air, water, or solid objects like a steel rod.





If you've ever seen a newton's cradle, sound waves are transmitted in much the same way. The compression wave is transmitted by a molecule being thrust forward until it transmits it's momentum into another molecule and so on. That's why there's no sound in a vacuum, there's not enough molecules to transmit the compression of the sound wave, and why the denser an object the faster sound will travel through it.





EM waves are unique and almost magical in a way. They don't need a medium to be transmitted, in fact they move at light speed and are self propogating.





The electrical half generates a magnetic half of a wave, then the magnetic half generates the other electrical half of the electrical wave, which generates the other half of the magnetic wave, and the cycle repeats from there. So with that method EM waves don't require a medium for transmission.





I hope this helps you out.
Reply:This is technically true. Sound requires a medium of transmission to exhibit energy waves. Sound is not energy therefore it needs a medium to be transfered.





Electromagnetic waves require 'Free Space' to propogate energy.





Because 'free space' is always in existence its assumed that electromagnetic waves do not require any other medium to be transferred.